#help-38

1 messages · Page 59 of 1

dapper swift
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then we can do a substitution

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replace 2^x with u everywhere

wraith garden
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how

dapper swift
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$(2^x)^2 + 3 \cdot 2^x + 4 = 0$

solid kilnBOT
dapper swift
#

becomes $u^2 + 3 \cdot u + 4 = 0$

solid kilnBOT
wraith garden
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what is u

dapper swift
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u = 2^x

wraith garden
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u substriture?

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substiture**

dapper swift
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yes

wraith garden
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is it

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$u^2+u+7$

solid kilnBOT
wraith garden
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is that final answer

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or we do

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(u+4)(u-3)

dapper swift
solid kilnBOT
dapper swift
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shit this one isn't factorisable sorry

wraith garden
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how do u factor something unfactoriable

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???W

dapper swift
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you have to use the quadratic formula

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you'll get imaginary numbers

wraith garden
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the long sh

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no

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:((

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i hate formulas

wraith garden
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i really hate formulas

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cuz u have to memorize so long

dapper swift
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don't worry your problems won't be this nasty

wraith garden
dapper swift
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do you have any textbooks?

wraith garden
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can u solve this

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.

wraith garden
wraith garden
dapper swift
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you just need to use the prime factorisation

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you want the powers of 2 and 5 from 30^9

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cause 400,000 is only made up of powers of 2 and 5

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so that gives 10^9 = 2^9 * 5^9

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and 400,000 = 4 * 100,000 = 2^2 * 2^5 * 5^5 = 2^7 * 5^5

wraith garden
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how

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what is the 30^9 for?

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im actually a competitor for math olympiad, idk how i qualified

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😆

wraith garden
dapper swift
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oh wait you do need the 3^9

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so 30^9 = 10^9 * 3^9

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so 2^9* 5^9 * 3^9

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yeah so if you have 2^7 * 5^5 that will work

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if you have 2^7 * 5^5 * 3 that will work

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if you have 2^7 * 5^6 that will also work

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as long as you're under 30^9 = 2^9 * 5^9 * 3^9

dapper swift
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such that it's between 7 and 9?

wraith garden
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uhh

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hAHHSHS

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sorry bro

wraith garden
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$oh wait you do need the 3^9
so 30^9 = 10^9 * 3^9
so 2^9* 5^9 * 3^9
yeah so if you have 2^7 * 5^5 that will work
if you have 2^7 * 5^5 * 3 that will work
if you have 2^7 * 5^6 that will also work
as long as you're under 30^9 = 2^9 * 5^9 * 3^9$

solid kilnBOT
dapper swift
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like 300 and 10 for example

wraith garden
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30?

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is it 30

dapper swift
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nah 300

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so 300 = 3 * 100 = 3 * 2^2 * 5^2 right

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and 10 = 2 * 5

wraith garden
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yes

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yes

dapper swift
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so 2^2 * 5 will work

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cause (2^2 * 5)/(2 * 5) = 2

wraith garden
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$cause (2^2 * 5)/(2 * 5) = 2$

solid kilnBOT
wraith garden
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yes

dapper swift
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so we just need to choose a power that is 2^1 or greater

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and a power of 5^1 or greater

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as it will divide evenly into 10

wraith garden
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so $300 = 3 * 100 = 3 * 2^2 * 5^2 right$

solid kilnBOT
dapper swift
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yeah

wraith garden
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where did the 5^2 go

dapper swift
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we're considering the 10

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not the 300

wraith garden
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so it disappear?

dapper swift
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no

dapper swift
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and 50/10 = 5 right

wraith garden
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yes

dapper swift
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20 and 50 are all multiples of 10

wraith garden
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yes

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they produce

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whole no

dapper swift
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so if our prime factorisation has 2 * 5 or greater

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it will also be a multiple of 10

wraith garden
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what does greater mean

dapper swift
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more

wraith garden
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examples

dapper swift
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if it's a multiple of 2 * 5

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like 2 * 2 * 5 = 2 * (2 * 5), it's a multiple of 10

wraith garden
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ohhhhh

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however u do it

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its still multiple of 10

dapper swift
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yeah

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but it has to be less than 300 though

wraith garden
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2 * 5 * 0.5 is 5 tho

dapper swift
wraith garden
wraith garden
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how do we determine

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its less than 300

dapper swift
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right, so for the powers of 2

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we have 2^2 in 300

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and 2^1 in 10

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that means our power of 2 can either be 1 or 2

wraith garden
dapper swift
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so like 2^2 * 5 = 20, a multiple of 10

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2^1 * 5 = 10, a multiple of 10

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2^2 * 3 * 5 = 60, a multiple of 10

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but we can't have 2^3 * 5 = 40

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that's a multiple of 10

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but it doesn't divide evenly into 300

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cause 300 = 3 * 2^2 * 5^2

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only has a power of 2^2

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in other words, the maximum power of 2 that can divide evenly into 300

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is 2^2 = 4

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so 2^3 = 8 or any higher won't work

wraith garden
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so that means

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3?

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or 8..

wraith garden
dapper swift
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so there are only two choices for our power of 2

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2^1 or 2^2

wraith garden
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hm

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i still odnt understand bro

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HUHUHU

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i hope u get my situatuion

dapper swift
dapper swift
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specifically prime factorisation

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and combinatorics

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cause this is the example with 300 and 10

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the original question has much larger numbers

wraith garden
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i actually know the prime factors

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but

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idk how to use it

dapper swift
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you don't know combinatorics right

dapper swift
wraith garden
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no

wraith garden
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what is the prime factor of 100

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i know

dapper swift
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yeah but there's no point then

wraith garden
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but idk how to use

dapper swift
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like say 72

wraith garden
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72

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36(2)

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then

dapper swift
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yep

wraith garden
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12(3)(2)

dapper swift
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yeah

wraith garden
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(3)(2)(2)(3)(2)

dapper swift
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yep!

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so what's that using exponents?

wraith garden
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(2^2)(3^2)(2)

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$(2^2)(3^2)(2)$

solid kilnBOT
dapper swift
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yeah nearly there

wraith garden
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how

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i know how to prime factor but idk when to use

dapper swift
solid kilnBOT
dapper swift
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yeah so you can do it

dapper swift
wraith garden
dapper swift
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idk

wraith garden
dapper swift
wraith garden
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i didnt expect to get in

dapper swift
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lol

wraith garden
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so whats the answer?

dapper swift
wraith garden
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300 and 19

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10

dapper swift
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oh for 300 and 10

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that's easier thank god

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I was trying to do the original one

wraith garden
dapper swift
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yeah so 300 = 3 * 2^2 * 5^2

wraith garden
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so go for the smaller

dapper swift
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and 10 = 2 * 5

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so (2 - 1 + 1) = 2 choices for the 2
(2 - 1 + 1) = 2 choices for the 5

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and (1 - 0 + 1) = 2 choices for the 3

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so 2 * 2 * 2 = 8

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if you count there are 8

wraith garden
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but it shows 18

dapper swift
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10, 20, 30, 50, 60, 100, 150, 300

wraith garden
dapper swift
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that's the same as 10 - 1 + 1 = 10

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so we're finding how many numbers there are between 1 and 2

wraith garden
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2?

dapper swift
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yeah

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you can think of it as 2 - 1 + 1 = 2

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adding 1

wraith garden
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so its completely useless?

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since answer is 0

dapper swift
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nah

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2 - 1 = 1

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1 + 1 = 2

wraith garden
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eh

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2 5 3 are the main prime factors right

dapper swift
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yes

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btw you can get 18 divisors in total

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you can choose 3^0 or 3^1

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2^0, 2^1, 2^2

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and 5^0, 5^1, 5^2

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so 2 * 3 * 3 = 18 choices in total

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18 divisors

wraith garden
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;-;

dapper swift
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yeah that's the principle behind it

wraith garden
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should i quit math

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lol

dapper swift
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nah

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you just need more time

unreal eagle
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so u say tht you are struggling with variables(e.g: x, y)?

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@wraith garden

wraith garden
unreal eagle
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like rational function?

wraith garden
unreal eagle
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can you give me an example, maybe that can help

wraith garden
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like

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quadratic equations

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and the letter e

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#

@wraith garden Has your question been resolved?

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@wraith garden Has your question been resolved?

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jaunty topaz
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#

@jaunty topaz Has your question been resolved?

jaunty topaz
#

<@&286206848099549185>

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do i just multiple each y value by its corresponding joint probability?

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and add them togethe

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@jaunty topaz Has your question been resolved?

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magic cosmos
#

I don’t remember what gets that summation be negative and then positive

magic cosmos
#

I see that it goes to 10, being squared, though I don’t see how to get the minus and addition in it

delicate belfry
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What is (-1)^2 and (-1)^3 ?

magic cosmos
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1 and -1

delicate belfry
#

Exactly, -1 changes depending whether the power is odd or even.

magic cosmos
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Yes

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But those summations are being squared

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Like n^-2

delicate belfry
#

Still, it doesn't matter how the sequence change, put a - sign infront, it still changes.

magic cosmos
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Hmhm

delicate belfry
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See how the sequence appear with $-\frac{1}{n^2}$

buoyant trench
#

Bot is down

magic cosmos
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Oh

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It be continuous negative fractions

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Ooo

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-1^n/n^2

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Nah

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-1^n/-n^2

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Yh it is that

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Thank u

#

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wraith hinge
#

Basically solving this term (sequences and series)

surreal bough
#

rearrange the terms

wraith hinge
surreal bough
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oh nice

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let me see

wraith hinge
wraith hinge
surreal bough
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hm

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I got something different

wraith hinge
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How

surreal bough
#

your answer is negative

wraith hinge
#

Yes

surreal bough
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but by inspection I think the answer should be positive

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logically

wraith hinge
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True

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But the thing is

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Where does the -8 term go?

surreal bough
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what do you mean?

wraith hinge
#

The 8,64,512

surreal bough
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yes

wraith hinge
#

Has a negative sign before it

surreal bough
#

yes

wraith hinge
#

So the sum of GP also has a negative sign before it

surreal bough
#

yes

wraith hinge
#

So where am I wrong

surreal bough
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try it this way

wraith hinge
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Sum of 30 powers of 2

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-twice the sum of 2^3+2^6...?

surreal bough
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((2+4)+(16+32)+(128+256). . .) - (8+64+512))

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or

wraith hinge
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Shouldn't the last bracket be positive?

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-(8+64+512)

surreal bough
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yes

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sorry

wraith hinge
#

Man this is confusing 😭

surreal bough
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(6+48+384...) - (8+64+512...)

wraith hinge
surreal bough
#

two geometric series

wraith hinge
#

Hmm

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But why is my answer wrong

surreal bough
#

let me see

wraith hinge
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This is the given answer

surreal bough
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from the given

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let me try it that way hold on

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I don't get the given answer either

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$\frac{2(8^{36} -1)}{7} + \frac{4(8^{36}-1)}{7} - \frac{8(8^{18}-1)}{7}$

solid kilnBOT
surreal bough
#

aren't these the correct exponents?

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there aren't 30 negative terms in the sequence.

surreal bough
#

there's 36,36,18 not 30,30,30

wraith hinge
#

Since -8 is the 3rd term the 90th term will be from the -8 series

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Hence the remaining will also be 30 and 30

wraith hinge
surreal bough
#

I mean

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look at the sequence

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for every 4 positive terms

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there's 1 negative term

wraith hinge
#

Uhm

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For every 2 positive term

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There's a negative term

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2,4,-8

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16,32,-64

surreal bough
#

oh what ur right hold on I'm tripping

wraith hinge
#

128,256,-512

wraith hinge
surreal bough
#

wow that was big mind blunder

wraith hinge
#

We will get there together

wraith hinge
surreal bough
#

ok wait with this newfound knowledge

wraith hinge
#

I just don't understand how he just adds these up and brings it to 14/7 [~]

surreal bough
#

no I see that

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wait it's 142/7

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right

wraith hinge
#

No..?

surreal bough
#

wait

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I can't read his writing

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what does it say

wraith hinge
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He took 8^30 -1

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Common

surreal bough
#

yes

wraith hinge
#

He divided it

surreal bough
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oh

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u know some people write the 7s

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with the cross

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so I thought that was that

wraith hinge
wraith hinge
surreal bough
#

yes I see now

wraith hinge
#

Let me complete the lec and check in again

surreal bough
#

he wrote it incorrectly here?

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why is it 2(8)^30-1 and not 2(8^30-1)

wraith hinge
#

Bro...

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He corrected it

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I should have watched the entire thing 😭

surreal bough
#

ohh lmao

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I was tripping hard

wraith hinge
surreal bough
#

not same thing doe

wraith hinge
#

He probably forgot to add the bracket

surreal bough
#

ye probs

wraith hinge
#

Does that sometimes

surreal bough
#

lmao what

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ok

wraith hinge
surreal bough
#

ah great

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it worked out

wraith hinge
#

Corrected it lmao

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Yeah

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Thanks

#

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daring meteor
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cedar flower
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# daring meteor
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
daring meteor
#

idk how to solve

#

ig 7

cedar flower
#

okay, can you do g(5)?

daring meteor
#

uhh no?

cedar flower
#

why not?

daring meteor
#

cause idk how to

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solve

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complicated for me

proven hound
#

Just substitute x=5 in g(x)

daring meteor
#

i know but what does the small 3 do

cedar flower
#

cube root

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if x^3 = y then cube root of y is x

daring meteor
#

g(x) = 3 i think

cedar flower
#

well not quite, g(5) = 3

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it's only true when x=5, not when x is anything

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okay, so now we have g(5)=3 - what's f(3)

daring meteor
#

so x is 5?

cedar flower
#

we have set x=5 in g(x) and gotten 3.

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and now we want to calculate f(x) where x=g(5), which means when x=3.

daring meteor
#

f(3) is 5?

cedar flower
#

looks like it, yeah

daring meteor
#

so what's f(g(5))

cedar flower
#

well g(5) = 3, so we can replace g(5) with 3

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and so f(g(5)) = f(3)

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and f(3) = 5

daring meteor
#

so its 5?

cedar flower
#

yes

daring meteor
#

tysm

#

ima close rn

#

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stone garnet
#

For differentiation, does dx^2 equal to 2xdx? If yes, what is the logic and the meaning of d?

stone garnet
#

Okay so afaik, d/dx means derivative

#

So if dx^2/dx = 2x

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Then I can say that dx^2 =2xdx

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Seems correct but what is the logic here? What do d and dx indicate and why am I allowed to multiply and divide with them as if they are some numbers

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@stone garnet Has your question been resolved?

golden vale
#

but they are very small so we represent them by "d" or delta

tardy hemlock
#

(this allows for the chain rule, for example)

#

There is a very popular question about this on MSE

#

See the first answer there

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still stirrup
#

Determine a point and a direction vector of each of the lines that have the following equations:

still stirrup
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celest beacon
#

How can you tell which function is represented in a graph?!!

stark bison
#

Mostly it's just guessing from experience

celest beacon
celest beacon
stark bison
#

If you were given a graph and asked what function is presented on the graph, you would need to guess

celest beacon
#

oh ok!

#

How do you find a domain if it does not touch the x- intercept in the graph?!

stark bison
#

I suppose you mean the x-axis

celest beacon
#

Yeah I do, sorry about that!! xd

stark bison
#

Not touching the x-axis is irrelevant to the domain though, you might want to rephrase the question

celest beacon
#

I guess my brain got comjumbled with information!

#

How do I find the domain of a parabola?

stark bison
#

Usually parabolas are defined on the entire set of real numbers

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So, if you are given a graph with no points missing, you should be safe to assume that the domain is R

#

But if any points are missing, exclude their x-coordinates from R

celest beacon
#

ok!!

#

What is an end behavior for lines in a graph?!

stark bison
#

thonk Depends on the context I guess, how does the graph look?

celest beacon
#

The line is l-shaped, meaning it is an Exponential graph!!

#

The function is g(x)=2(0.5) to the power of x.

stark bison
#

I guess what they are expecting you to say is that the graph approaches the x-axis (or, simply, that the x-axis is its asymptote)

celest beacon
#

It is asking which has the same end behavior for large, positive values of x!!

celest beacon
#

ok thank you!

#

How do you find the initial value on a graph?

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pallid cedar
#

Need help on question 12. Don’t know how to start

pallid cedar
#

!status

trim joltBOT
#
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
pallid cedar
#

1

wraith hinge
#

Hi, can you crop number 12 and send it here?

pallid cedar
#

ok

wraith hinge
#

Appreciate it. 🙂

pallid cedar
wraith hinge
#

Let me solve it for you?

pallid cedar
#

if i can just find out how to start i think i'll be able to do the rest

wraith hinge
#

Ok

#

Equate 2x + 20 and 5x - 37

#

to find the value of x and plug in the value to find the measurement

pallid cedar
wraith hinge
#

Wait

#

this is FGH?

pallid cedar
wraith hinge
#

Ok hold on, wrong. I apologize

pallid cedar
#

the paper in general is about the perpendicular bisector theorem (and its converse), and the angle bisector theorem (and its converse)

rough grotto
#

try to establish a relationship between traingles FIG and HIG

pallid cedar
#

i found that side IG is shared between both triangles

#

so i put the 2 lines

rough grotto
#

also do notice both are right-angled triangles

pallid cedar
#

yeah

wraith hinge
#

Oh i checked it again

#

They are really equal

pallid cedar
wraith hinge
#

Solve for x

rough grotto
#

so basically SSA does not mean congruent

pallid cedar
#

ik

#

it's SAS, SAS, AAS, ASA, HL

#

right?

rough grotto
#

but since the angle is 90 degree the other side has to be same

#

I did not learn HL at school..but yes this is a case of HL that you have mentioned

pallid cedar
#

so i can say congruent because HL?

rough grotto
#

yep

pallid cedar
#

ok one last question about this specific problem

rough grotto
#

yes tell me

pallid cedar
#

how do i know that 2x+20 is equal to 5x-37 and not the other angle in IGH (besides 5x-37 and the right angle)

rough grotto
#

that is based on ordering

pallid cedar
#

?

#

i don't understand

rough grotto
#

we say triangle FGI is congruent to HGI

pallid cedar
#

oh yeah

rough grotto
#

but we can't say triangle FGI is congruent to GIH or IGH

pallid cedar
#

so f=h, g=g, and i=i

rough grotto
pallid cedar
#

oh i get it now

#

thanks

#

thank you for your time

#

appreciate it

rough grotto
#

no problem

pallid cedar
#

.close

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#
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safe flower
#

im sorry if this isnt the correct server to ask but

safe flower
#

how do u get the volume of a cube here

cedar flower
#

you know the side length

#

so you know the volume

safe flower
#

which the formula is a^3

#

its stated here, however that it is mm but the density is cm^3

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@safe flower Has your question been resolved?

safe flower
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daring karma
#

what is the dot product of 2 parallel vectors?

daring karma
#

it's the absolute value of 1, right?

left oriole
#

what do you think it should be?

daring karma
#

the absolute value of the dot product hsould be 1, right?

left oriole
#

if they are unit vectors then yes

#

otherwise not necessarily

daring karma
#

and if they are not?

left oriole
#

are you familiar with
$$a\cdot b = |a| |b|\cos(\theta)$$

solid kilnBOT
daring karma
#

forgot about that. So if they're parallel, then cos(theta) is 1.

left oriole
#

or -1

daring karma
#

So the dot product of parallel vectors is the product of their magnitudes

left oriole
#

but then take abs value, it's 1

daring karma
#

so am i right in saying that if vectosr are parallel, the dot product is the product of their magnitudes

#

well you need to look at its abs value tho

left oriole
#

the abs value of the dot product is the product of their magnitudes

daring karma
#

right

left oriole
#

the dot product itself is either + or - the product of their magnitudes

daring karma
#

okay thank you so much

left oriole
#

sure, gl

daring karma
#

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worthy eagle
#

Hey quick question, do RYA(reflection in y-axis) makes points for x-axis and RXA(reflection in y-axis) in y-axis when making a new points?

For example,
\begin{enumerate}
\item (f(x)=\frac{1}{2}(2)^{-x+4} -8)
\begin{itemize}
\item \textcolor{red}{VS by 2}
\item \textcolor{red}{RYA}
\item \textcolor{red}{HT 4 (\to)}
\item \textcolor{red}{VT 6 (\uparrow)}
\end{itemize}
\end{enumerate}

My new key points from the equation above makes new point for x as \
$\boxed{\textcolor{OrangeRed}{-x-4}}$ and for y $\boxed{\textcolor{Melon}{2y-8}}$

but why?

solid kilnBOT
#

Akira (fumo)

worthy eagle
#

I want to understand why RYA goes to x section instead of y

#

does this mean same thing goes for RXA but for y-axis?

#

I can show my paper to see what my teacher did im kinda confused

#

<@&286206848099549185>

unique minnow
#

I'm not sure I understand what you mean by "making points for x-axis". What about "new points"?

Are you describing f(x) in terms of translations and reflections? Or are you starting from f(x) and then saying that the point (x, y) is mapped to (-x-4 , 2y-8) after the transformations?

worthy eagle
unique minnow
#

OK, so if I got this right, you're wondering why reflecting about the Y-axis changes the sign of x, and why reflecting about the X-axis changes the sign of y?

worthy eagle
#

yes

#

checking the examples from my practice sheet, it's always like that?

unique minnow
#

A point is mapped to it's mirror image with respect to the x axis. The same distance from it, but the other way.

#

Functions are just collections of points really, so a reflection about the x-asix applied to a function will change the sign of all y coordinates.

#

This is the other one, same distance to the y axis, but on the other side.

worthy eagle
# worthy eagle checking the examples from my practice sheet, it's always like that?

Oh alright I was thinking that, in page 2 where it says $f(x)=-2\left(\frac{1}{2} \right)^{x+4}+8$. When we write transformation in the equation it has RXA. So, the y-axis will be $-2y+8$. Same thing in page 3 where it says $f(x)=\frac{1}{2}(2)^{-x+4} -8$ it has RYA. So -x-4 right? Does this apply to every example? I know how transformations works in other but just getting confused about reflections

solid kilnBOT
#

Akira (fumo)

worthy eagle
#

But I think I got it now

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karmic solar
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karmic solar
#

Could someone describe how this equation works?

trim joltBOT
#

@karmic solar Has your question been resolved?

karmic solar
#

<@&286206848099549185>

#

.close

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crisp rivet
#

Can someone help me with this question

crisp rivet
#

i got the big radius as 1-y^2

#

and small radius as 4

#

and i set up the integration but I'm not getting the right answer

fossil kraken
#

As a first thought, you might want to explain the question a little more. We do not all have your context. I guess you are after a volume of something 3D? Not obvious what the x=4 has to do with the curve, without a lot of guessing.

crisp rivet
#

oh yea

#

my bad lol

#

im trying to find the volume of the solid created by revolving the region bounded by the graphs

versed fractal
#

I’m assuming interior area here is between x=4 and x=5-y^2 and you need to find the solid if revolution using the ring method

#

So here what you want to do is find the intersecting points of both graphs to find the bounds of your integration. Since this is around the y-axis you want to find the area between curves down to the y-axis.

#

Your integral should look something like this

#

Where R is the exterior curve and r is the interior curve

trim joltBOT
#

@crisp rivet Has your question been resolved?

#
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wraith hinge
trim joltBOT
wraith hinge
#

I'm getting stuck here

versed fractal
#

are you proving a statement here?

wraith hinge
#

I'm proving one side is equal to the other, yes

wraith hinge
versed fractal
#

workin on it

wraith hinge
#

alright, because according to desmos

#

it's matching

#

wait

#

no it isn't

#

not matching

#

gotta check my algebra

#

nvm

#

it is

#

mistyped

#

lol

#

nvm I got it

#

the trick was

#

to factor out cos^2y

#

from the first two things

#

in ba+ab+c, I factored out b

versed fractal
#

Yeah I was kinda getting those steps

#

This was one of the trickier ones to do

trim joltBOT
#

@wraith hinge Has your question been resolved?

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wraith hinge
trim joltBOT
wraith hinge
#

I can’t get -2 as the answer no matter how hard I try

#

I know how to solve it but I just can’t get the answer I’m looking for

trim joltBOT
#

Show your work, and if possible, explain where you are stuck.

unique pine
#

What did you try

wraith hinge
#

I subtracted one equation from that side to get

#

(X+5) - (5-2x)

trim joltBOT
#

@wraith hinge Has your question been resolved?

wraith hinge
#

.close

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#
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opaque rampart
#

I understand you have to bring out the 10. I just don’t get what to do afterwards.

opaque rampart
#

.close

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fading narwhal
#

Hello! I’ve got three questions that I’m not sure how to start on. I really just need to be walked through the actual steps of completing them.

Thank you

fading narwhal
#

To whoever helps me, we can start with the antidepressant question.

pallid lake
#

Hi

fading narwhal
#

Hello

pallid lake
#

what is the problem with the first question?

fading narwhal
#

I’m not sure how to find the inverse of the function.

pallid lake
#

What I usually do is write f(x) as y and then switch x and y

#

and then solve for y

fading narwhal
#

So would my f(x)= -0.088x + 2.99 be written as:

y= 0.088x - 2.99

pallid lake
#

Yes

#

and then switch x and y

#

and solve for y

fading narwhal
#

So it would be 0.088y instead?

pallid lake
#

yes, -0,088y that is

fading narwhal
#

Okay thank you

#

Now this one also deals with inverse

pallid lake
fading narwhal
pallid lake
#

alright 👍

#

well same thing

#

switch y and x's place and solve for y

#

@fading narwhal Has your question been resolved?

fading narwhal
#

Okay cool, and the graph is symmetrical with respect to y = x I believe?

pallid lake
#

Yes

fading narwhal
#

Awesome

#

Okay last one

pallid lake
#

Great :D

#

Alright

fading narwhal
#

I have the scatter plot graphed

#

But I’m not sure how to find the function for it

#

I tried to use y1 ~ mx1 + b and got the regressions etc. for it, but I’m not sure that’s what I’m even supposed to do

pallid lake
#

well it states in question a that it's an exponential function

#

so that gives us some information, such as that the function in question must be of the form y = a^x + b

fading narwhal
#

I’m not really sure what A and B are in this problem

pallid lake
#

We can solve for b by looking at the first value.

#

If we take 1955 as the 0 for this graph

#

we know that b must be 407,8

#

since a^0 = 1

#

we can solve for a by plugging in values

fading narwhal
#

So right now we are at:

y = a^0 + 408.8

pallid lake
#

Close

fading narwhal
#

I’m a little lost I think 😂

pallid lake
#

We have y = a^x + 407,8

#

if we plug in x = 10 and y = 835,5

#

we can solve for a

fading narwhal
#

Why is it 407, 8? Is that an ordered pair?

pallid lake
#

the first value is 408,8 yes?

#

that is at x = 0 since we're saying that 1955 is the x coordinate of 0

#

if we put in x = 0 at the function we get 1

#

a^0 = 1

#

if we did not subtract 1 from the last part we'd have 409,8 which is not equal to the first y coordinate we have

fading narwhal
#

Okay I’m on board now

pallid lake
#

Hahaha great XD

#

then we can fill in multiple values of x and y to get something that's close to a

fading narwhal
#

I lied, maybe I’m not on board. Everything looks like word soup to me right now, sorry 😭

#

Okay hold on hold on

pallid lake
#

Does your book define an exponential function?

#

or is it not shown

fading narwhal
#

This is where I’m at

fading narwhal
pallid lake
#

Alright

#

you want to know 'a' right?

#

at least, a close enough value that fits with your table of values

fading narwhal
#

I think I’m just trying to get the actual function equation itself

pallid lake
fading narwhal
#

I’m losing it a little bit, I’ve been doing math since ~6am this morning 😭

pallid lake
#

Hahaha no worries

pallid lake
#

with every x and y value

#

so first off fill in x = 10 and y = 835.5 and solve for a

fading narwhal
#

Like that

pallid lake
#

Yes

#

and for y = 835,5

#

next x = 20 and 2306,5

#

Hold on gotta see if im correct first

fading narwhal
#

Your commas are supposed to be decimals, right?

pallid lake
#

Yes sorry in my country

#

they're decimals

fading narwhal
#

Oh I gotcha, no worries 👍

#

I was seeing them at ordered pairs at first, and that added to my confusion, sorry lol

pallid lake
#

haha no problem

fading narwhal
#

I’m blanking right now. How do I solve for a

#

I’m embarrassed for asking 😭

#

I need to

pallid lake
#

It's no problem!!

#

No worries

#

Im trying to find it myself too

#

takes a while XD

fading narwhal
#

Ah I gotcha lol

pallid lake
#

Hold on a sec

fading narwhal
#

I’ve found B) and C)

#

Okay

pallid lake
#

alright

#

So the exponential function is N = b g^T

#

with b as starting number and g the growing factor

#

and t is time

fading narwhal
#

N = 0 408.8^t ?

pallid lake
#

N = 408,8 g^t

#

I understand your confusion this is hard :(

#

but I now know how to solve it

#

Forget Everything I told you

fading narwhal
#

Okay lol

pallid lake
#

im checking if what i did was right lolol

fading narwhal
#

All good : )

#

If this helps at all

#

On the example problem for this one

#

They say the answer is this

#

So our answer has to be in that same form

#

y = 337.906 (1.084^x)

pallid lake
#

yes exactly

#

y = b g^x

#

Alright I know it

#

Pick 2 points and divide the highest by the lowest

fading narwhal
#

So like 10231.2 / 835.5 ?

#

I got 12.25

pallid lake
#

Yea that's fine

#

and then do root it the number of years apart

#

so for your point that's 35 years apart

#

so the 35th root of 12.25

fading narwhal
#

1.07

pallid lake
#

it's more exact if you instantly put the fraction to the power of 1/35

fading narwhal
#

1.074

pallid lake
#

so (10231/835,5)^1/35

#

Yesa

#

Correct

#

1,074

#

you can do it with more values to get a more exact a but this is basically it

#

so it's y = b 1,074^x

fading narwhal
#

Okay so that’s one half

pallid lake
#

and now solve for b

#

well b means the value for x = 0

#

and that's 408,8

fading narwhal
#

How do I solve for b

pallid lake
#

b = the value when x = 0

#

the text says that x = the number of years after 1955

#

so 1955 = (x = 0)

fading narwhal
#

Okay I’m confused again. This is the example problem here:

#

Why is their’s not 409.1 ?

pallid lake
#

Most likely because this question says that the starting year is not 1957

#

but some year after that

fading narwhal
#

Their starting year is 1957

pallid lake
#

I actually have no clue

#

it doesn't even work

#

I don't think that that equation is correct...

fading narwhal
#

That’s what my college gave us as the example question…

#

Well crap

fading narwhal
# fading narwhal

Okay just getting it back down here, this is the one we’re working on currently

pallid lake
#

well the answer to your question I THINK is: y = 408,8 (1,074)^x

#

yes devide the higher value with the lower value

#

and root it the difference in years

#

that's your growth factor

fading narwhal
#

Yeah we’ve got that part

pallid lake
#

and your b SHOULD BE when x = 0

fading narwhal
#

It’s just B that we need

pallid lake
#

but apparently your collage disagrees

#

so lets take a value for b

fading narwhal
#

Should we get another set of eyes on this in case there’s something we’re missing / not seeing?

pallid lake
#

I agree

#

Because this doesn't make sense

#

(to me)

#

:)

fading narwhal
#

Okay so

#

I don’t want to ping helpers, but is that what I should do?

fading narwhal
#

The rules say we get one if we don’t get help in 15 minutes, but I’m not sure what to do in this situation

#

Oh nvm

pallid lake
#

I think the example question is wrong because it really just doesn't make any sense at all

#

x = 0 should be 409,1 but the formula says 444,23

#

which just isn't correct

#

so I understand your confusion XD

fading narwhal
#

If it was just purely my college, then I’d think it was 100% wrong, but my professor is the one who helps us through the problems and this is what she got, and then the system itself said the answer was correct

#

So both my professor and college agree on it

#

But it sounds like it’s not even a possible answer

pallid lake
#

put in 0 for x in the example question

#

you won't get 409,1 right

#

I REALLY WANNA KNOW if im just crazy or if this question is wrong

fading narwhal
#

It just gave me 444.23 back

#

444.23(1.076^0) = 444.23

#

Is that what you were asking?

pallid lake
#

Yes

#

and what is the value for 1957 in the example question?

fading narwhal
#

I don’t think any of the helpers are here to help lol

pallid lake
#

Hahaha don't think so either

fading narwhal
#

409.1

pallid lake
#

Is 409,1 the same as 444,23

#

No

#

so the equation is straight up not correct

fading narwhal
#

We’ll try it

pallid lake
#

maybe they want an approximation

fading narwhal
#

If I press help me solve this, it runs through TI-84 instructions

#

Maybe I’ll try that with ours and see what we get?

pallid lake
#

Sure

#

I think they'll put in values for x and y to solve for the b value

#

For better approximation you can try more values but it's more work

fading narwhal
#

Okay interesting development

#

The second example problem is also different from the 0 value

pallid lake
#

I think I understand how they find that value now

fading narwhal
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337.906 instead of 400.5

pallid lake
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alright im gonna check my theory

fading narwhal
#

Okay 👍

pallid lake
#

I think your collage wants you to do this using the TI-84 calculator

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instead of calculating it by hand

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and sadly I don't know how to do it with calculator :(

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the different b value is caused by the calculator being able to do more calculations for the value

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a more exact value that is

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And I sadly have to go ;/

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Good luck though

fading narwhal
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I got 442.89

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Okay thanks

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Shit man. If anyone is still here now that he left, I’m still just a bit confused on some things.

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Anyone?

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.close

trim joltBOT
#
Channel closed

Closed by @fading narwhal

Use .reopen if this was a mistake.

#
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Show your work, and if possible, explain where you are stuck.
After 15 minutes, feel free to ping <@&286206848099549185>.
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elder field
trim joltBOT
elder field
#

Help quick

storm grove
#

Do you know what 12.3x10^8 is

elder field
#

No

storm grove
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As a number?

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so whats 12.3x100000000

elder field
#

Wait lemme put it in a calculator

storm grove
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Too many zeros

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Sry

elder field
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23

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23000000

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@storm grove

west nest
#

A number is usually written in scientific notation when a number between 1 and 10 is multiplied by a power of 10.

#

In your case, 12.3 * 10^8 can be written as 1.23 * 10^9

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But that isn't important

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You are pretty much multiplying two numbers written in scientific notation

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So (a number times a power of 10) times (a number times a power of 10)

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What 12.3 * 10^8 means is just that you are multiplying 12.3 with 100.000.000 (notice the 8 zeroes)

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If you had for example 5 * 10^4, this would mean 5 * 10.000 (5 zeroes), or 50.000

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Anyway

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You see that there's just a bunch of multiplication involved.

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If you need to solve this without a calculator, you need to know a few properties that multiplication and exponents have and this is a piece of cake

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Otherwise you can just plug it in a calculator ... 🙃

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mention me when you get back if you need me please

trim joltBOT
#

@elder field Has your question been resolved?

#
Channel closed

Closed by @elder field

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#
Available help channel!

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Remember:
Ask your math question in a clear, concise manner.
Show your work, and if possible, explain where you are stuck.
After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!

Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.

fading narwhal
#

Hello! I’ve been stuck on this for awhile. I think I’ve got the function and the other answers, but they rely on my function being correct, so I just want someone to help me fact check my answers.

(a) Function: y = 442.89(1.074^x)
(b) 15722.077
(c) 2008

fading narwhal
#

I’m just gonna assume that nobody is active. I’ve made three different channels trying to get this one problem, and the only helper I’ve gotten was also confused so we mutually decided to get a different set of eyes on this problem. I’ve been waiting 2 hours. I’ll try later today.

cinder swallow
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It might be easy to set up a LinearRegression model for this in Python.

low gazelle
#

Assuming ur suppose to use a regression line

fading narwhal
#

I tried a regression line in desmos and it didn’t appear to be accurate

low gazelle
fading narwhal
#

This was the example problem

fading narwhal
low gazelle
fading narwhal
#

Let’s do that so that I can make sure my answers are correct

low gazelle
#

Ok so linear regression line is of the form y=a+bx

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We are given the data is exponential though so we need to transform it a bit

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First step is to take the log of all the income. This will make the relation ship between year and log(personal income) linear

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so log(y)=a+bx is what we are finding a and b for now

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b=cov(x,log(y)), a = mean(log(y)) - b * mean(x)

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find that out then sub back into the equation and solve for y

fading narwhal
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OKay so

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Im not sure what my a b and x are

low gazelle
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in general, x is independent var, y is dependent var. b is usually given by cov(x,y)/var(x,y), but we needed to modify it cuz we transformed y values to log. a is usually given by mean(y)-b(mean(x)) but we needed to modify it again cuz we transformed y values to log

low gazelle
fading narwhal
#

Im sorry, everything is looking like word soup to me right now, i'm confused

low gazelle
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Did you learn about how to manually find linear regression lines or were u told to just use calculator

fading narwhal
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my professors taught me on the calculator and on desmos

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im not sure what var and cov are

low gazelle
#

I see

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I will try and figure that out then rq give me a moment

fading narwhal
#

okay thank you, sorry that i dont know these things

low gazelle
fading narwhal
#

So I was correct?

low gazelle
#

Yeah

fading narwhal
#

Awesome, sweet

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okay so for part b

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I just replace x with 50 and solve, correct?

low gazelle
#

yeah

fading narwhal
#

15722.0778 rounded 3 decimal places to 15722.078

low gazelle
#

ye

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what did u do for c. Im getting 2009

fading narwhal
#

I dont think I rounded my year up, I rounded down

low gazelle
#

same

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if I rounded up I would have got 2010

fading narwhal
#

shit am i messing up

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54.7 on the graph is when I reach 22000

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so 1955

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plus 54.7 is 2009.7

low gazelle
#

Yah

fading narwhal
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am I doing this wrong, it would round up right? cause its closer to 2010

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it says to round up, so the answer is actually 2010?

low gazelle
#

Maybe u could round up. I would say round down since its during the year 2009 that it is reached

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like 8 months into 2009 they reach 22tril

fading narwhal
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The problem specifically says round up to the nearest year in the directions, so would I do 2009 or 2010

low gazelle
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lol I cant read

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do 2010

fading narwhal
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okay so in totality

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y=442.89(1.074^x)

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15722.078

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2010

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i think that all checks out

low gazelle
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yeah