#help-23

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crisp lodge
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Now, how would you conclude the total number o fpages in Sam's case ?

cedar crystal
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hmm

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sorry @crisp lodge

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i went away for a bit

cedar crystal
crisp lodge
#

not quite

cedar crystal
#

hm

crisp lodge
#

sam's pace is FASTER than usual

cedar crystal
#

65x

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then right?

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cause thats his new pace

crisp lodge
#

which coincides with 2 parameters

cedar crystal
#

true

crisp lodge
cedar crystal
#

i think you would do

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  • 135
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then on top of that

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or minus

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im not sure

crisp lodge
#

form an equation first

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then we'll progress from there

cedar crystal
#

65x(

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@crisp lodge

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i think i got it

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is it

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65x = 65(x-4) + 135

crisp lodge
#

just one little thing

cedar crystal
#

what is that

crisp lodge
#

65x is reading 65 pages each day

cedar crystal
#

oh then

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60(x-4)

crisp lodge
#

noooo

cedar crystal
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im not quite sure

crisp lodge
#

60x

cedar crystal
#

ok

crisp lodge
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60x - is the standard case we're comparing to

cedar crystal
#

i understand

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so then

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it would be

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60x = 65(x-4) + 135

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i think so

crisp lodge
#

why think so?

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be confidence

cedar crystal
#

ok well i know so

crisp lodge
#

check what your equation is saying

cedar crystal
#

well it says

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that 60 day's

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well sorry

crisp lodge
cedar crystal
#

for reading 60 pages per day

crisp lodge
#

sort of a sanity check

cedar crystal
#

i dont know

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to be honest

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im thinking of every possibility

crisp lodge
#

60*x is the total amount of pages

cedar crystal
#

ok

crisp lodge
#

sam has read 65(x-4) so far, but he still has 135 pages togo

cedar crystal
#

yep

crisp lodge
#

so 135 is the complement to john's reading so far that would get him to 60x

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so the equation checks out

crisp lodge
#

sam***

cedar crystal
#

ok

crisp lodge
#

idk why I had john in my head lol

cedar crystal
#

lol

crisp lodge
#

_don't do math at 3 am _

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says him who does math at 3am

cedar crystal
#

hahaha

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wdym

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by

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complement

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@crisp lodge

crisp lodge
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like

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the missing part of a whole

cedar crystal
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oh ok

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so what would the equation be

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60x = 65(x-4) - 135

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??

crisp lodge
#

you mean +135?

cedar crystal
#

yea

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sorry

crisp lodge
#

then yea

cedar crystal
#

ok

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thank you

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๐Ÿ‘

crisp lodge
#

np :)

cedar crystal
#

.close

safe radishBOT
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hard venture
#

could someone help me with number c? Im not sure how to do partial derivative with summation

safe radishBOT
#

Please don't occupy multiple help channels.

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@hard venture Has your question been resolved?

hard venture
#

<@&286206848099549185>

fair dagger
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Can you explain what the issue is?

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If I am reading correctly they just want you to derivate this.

hard venture
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i have never dealt with a partial derivative with

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summation involved

fair dagger
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oh

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But you know partial derivatives otherwise?

hard venture
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yup

fair dagger
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Okay good

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I think it may be more obvious if you just write it out

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we can also fix K = 3 for a moment

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$$\frac{e^{z_k}}{e^{z_1} + e^{z_2} + e^{z_3}}$$

flat frigateBOT
fair dagger
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can you do it in this case?

hard venture
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yes, but why did u write it out like that?

fair dagger
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To make it more clear that it is literally just plain old summation ๐Ÿ™‚

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even if there is a fancy sum symbol

hard venture
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no i mean, why 3 terms?

fair dagger
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I want you to see the pattern

hard venture
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oh

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wait

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so i can do the partial derivative for $e^z_l$ and keep the summation part?

flat frigateBOT
#

An Actual Anxious Hamester

fair dagger
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Not sure what you mean by "keep".

hard venture
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can i show you my answer in a bit? @fair dagger

fair dagger
#

sure

hard venture
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Could you help me verify please?

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I would send the steps, but I wrote it in paper, and it is a mess

fair dagger
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,wolf d/da e^a/(e^a + e^b + e^c)

fair dagger
#

square in the denominator seems to be placed wrong

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also I think the sums somehow did not work out correctly.

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@hard venture Should we try work it out step by step?

hard venture
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i dont mind ๐Ÿ˜„

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at first i took the constants out

fair dagger
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constants? Which constants

hard venture
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$e^{z_k}$

flat frigateBOT
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An Actual Anxious Hamester

fair dagger
#

I don't think this is the place to start.

hard venture
#

oh

fair dagger
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When you derivate you need ot work your way from the outside inwards

hard venture
#

oh

fair dagger
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in this case the first thing to do would be to work with the quotient

hard venture
#

oh

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so $e^{z_k}$, right?

flat frigateBOT
#

An Actual Anxious Hamester

fair dagger
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if we want to apply the quotient rule for f(x) / g(x) we need to find the derivative of f(x) and g(x)

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$$f(z_k) = e^{z_k}$$ and $$\frac{df(z_k)}{d{z_k}} = e^{z_k}$$

flat frigateBOT
fair dagger
#

how about g?

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:
$$g(z_k) = \sum_{n=1}^K e^{z_n}$$

flat frigateBOT
hard venture
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@fair dagger Sorry, I had to check on my baby. I think I will take a rest for 30 minutes, been working since the morning! Sorry ๐Ÿ˜„

fair dagger
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Ok

safe radishBOT
#

@hard venture Has your question been resolved?

safe radishBOT
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lone crane
safe radishBOT
lone crane
#

Anyone can do this i wanna know whats the answer

blissful gate
#

what have you done so far

lone crane
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I got..

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847.692.....

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Im just wodnerong of thats correct or nott

twilit wadi
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how did you get that

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that seems off

lone crane
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551/65 x 100

blissful gate
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it is correct

lone crane
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Okay thank youuu

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Is there any way that could be easy when i see "reduction"?

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Or so like

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I just use the reduced percentage

blissful gate
#

hm? what do you mean?

twilit wadi
lone crane
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Like for example what i did was i made 2 bars and first bar i put 65% and the second bar 35, we need the original price which has the percentage 65 and not the 35 since 35 is for the reduction price i assume?

twilit wadi
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and not 65 percent off?

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shouldn't you be using 35 instead of 65?

lone crane
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Yeah thats where iam confused

twilit wadi
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it's reduced by 65%

blissful gate
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good catch!

twilit wadi
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thanks :)

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we can set it up as an equation:

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0.35x=551

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solve for x

lone crane
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551/35?

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X 100

twilit wadi
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yes

lone crane
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Okayyokay

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But i still sisnt get it

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We are finding the original price right?

twilit wadi
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yeah

lone crane
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Since its the original thenn it has the 100% and the reduced price is.. 551
So 100-65 is 35
551 =35%

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And so on

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Correct?

twilit wadi
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yea

lone crane
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The ans is..

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192.85

twilit wadi
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?

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how would it be smaller?

lone crane
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I dont know..

twilit wadi
#

if a store applys a discount to an item and it gets more expensive, it's not much of a discount innit?

#

let's try solving it

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0.35x=551

lone crane
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551/0.35

twilit wadi
#

yes

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have a calc handy?

lone crane
#

Yeee

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1574.285..*

twilit wadi
#

yes

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attaboy

lone crane
#

Okayy umm last thing iss

twilit wadi
#

ye?

lone crane
#

Thiss

twilit wadi
#

0.80x=500

lone crane
#

Waiit let me solve it mate

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๐Ÿฅฒ

twilit wadi
#

dw dw

lone crane
#

100-20=80%

twilit wadi
#

mhm

lone crane
#

500=80%
Which is 500=0.80x
500/0.80 isss

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,calc 500/0.80

flat frigateBOT
#

Result:

625
lone crane
#

YYYYYESSSS

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Tyyyyssmmmm@twilit wadi @blissful gate i reallly appreicate it

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Take care and stay safe

twilit wadi
#

dw

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:)

blissful gate
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that was all bremperor!

lone crane
#

Wait if it ws

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Finsing reduction price

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Original - reduction ye?

twilit wadi
#

could you clarify it a little?

lone crane
#

Okayy sooo

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Finding the price the has been reduced

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Since we got the original price which is 625

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625 - 500

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Is 125

twilit wadi
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sure

lone crane
#

That is the redudced price ye?

twilit wadi
#

that is the amount the original price is reduced by

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yes

lone crane
#

Okayyy tysmm agaginn really appreicate it

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Take care n stay safe

twilit wadi
#

u as well

lone crane
#

:)))

#

.close

safe radishBOT
#
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languid brook
#

how do i calculate the area of a triangle with 3 points on the coord plane given

steel stag
#

shoelace formula*

thin token
languid brook
#

ok thx

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are there no absolute values?

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<@&286206848099549185>

red glen
languid brook
#

i got a negative area

red glen
#

Area can be negative

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Make remove that negative

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Answrr

languid brook
#

oh ok

red glen
#

Take absolute value

languid brook
#

ok

#

thanks

#

.close

safe radishBOT
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rugged hound
safe radishBOT
plucky elk
#

Jesus this problem

lime robin
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Can I get some help please

rugged hound
#

um sorry this channel is occupied lol

plucky elk
rugged hound
#

how do i find the side of the equilateral triangle

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<@&286206848099549185>

plucky elk
#

Is one side 5-2x^2?

rugged hound
#

is the side 2*sqrt(5-y)

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y=5-x^2, x=sqrt(5-y)

plucky elk
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are the cross sections parallel to the xz plane?

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i guess so since that's the definition of perpendicular to the y-axis

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,w plot y=x^2, y=5-x^2, y= 5/2

rugged hound
#

alright

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i think i figured it out then

#

.close

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desert hinge
#

i can do part a for q 9 and 10 but not part b

worthy hemlock
safe radishBOT
#

@desert hinge Has your question been resolved?

desert hinge
#

Part a

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Part b (attempt)

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when I do 48828125x1677216 I get 8.18953124 x 10^13 in my calc

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@weak dirge @worthy hemlock

worthy hemlock
#

You can use your answer from part a to do part b

desert hinge
#

oh my god you can

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thank you!

worthy hemlock
#

Same thing for 10

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And the others, I suggest that you simplify then plug in the values

safe radishBOT
#

@desert hinge Has your question been resolved?

prime prawn
#

,rotate

flat frigateBOT
desert hinge
#

im confused with 11

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so i simplified (a^4)^3 = a^12

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but a = (2/3)^1/6

red glen
red glen
#

Put a and b and get answer

safe radishBOT
#

@desert hinge Has your question been resolved?

lean otter
#

,calc (2/3)^1/6

flat frigateBOT
#

Result:

0.11111111111111
lean otter
#

hey @desert hinge

#

is the answer for 11

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4/9

#

?

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,calc ((2/3)^1/6)^12

flat frigateBOT
#

Result:

3.5407061614721e-12
lean otter
#

,calc simplify ((2/3)^1/6)^12

flat frigateBOT
#

The following error occured while calculating:
Error: Unexpected type of argument in function pow (expected: number or Complex or BigNumber or Fraction or Unit or Array or Matrix or string or boolean, actual: Node, index: 0)

safe radishBOT
#
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opaque wedge
safe radishBOT
opaque wedge
#

Hi

#

Pls help Iโ€™m stuck with this

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20 overs = 20x6=120

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50overs= 50x6=300

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<@&286206848099549185>

quasi bison
#

why are you multiplying 20 and 50 by 6?

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one would think that ||a sensible first step would be to find how many runs they have already, hence find how many runs they have left to score, and how many overs they have left to do it||

mortal meteor
#

yes, good idea

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and how many runs do they have already?

quasi bison
#

let OP respond

mortal meteor
#

ups, i didn't pay attention to the name

lean otter
#

@opaque wedge

safe radishBOT
#

@opaque wedge Has your question been resolved?

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thin token
#

please can someone tell me how to solve recurrence relation

thin token
#

and if possible please also provide some resources

frigid geyser
#

wikipedia

#

google

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(seriously, just google it, there are a ton of sites)

thin token
#

well ok

#

thanks a lot

#

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safe radishBOT
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lean otter
safe radishBOT
lean otter
#

Then I need the same if B is just a prebase.

#

Thanks in advance! Don't solve it for me, just point me in the right direction, please. I want to understand it.

ruby rapids
lean otter
#

And a base is only open sets, right?

#

If so, then I have the forward direction.

ruby rapids
#

well yes a basis consists of open sets

#

but more than that

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every open set is a union of basis elements

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by definition of a basis

#

likewise, every open set is a union of finite intersections of subbasis elements, by definition of a subbasis

lean otter
#

And since all open sets in the topology for X can be constructed from sets S in the basis B, all open sets U have open preimages if all sets S do?

#

So that's the other direction?

lean otter
ruby rapids
lean otter
#

My book actually doesn't use the terms, apparently.

ruby rapids
lean otter
lean otter
ruby rapids
lean otter
#

For a bijection.

ruby rapids
#

preimages generally behave well with respecto to most set-operations

ruby rapids
#

for any function between sets, you have $f^{-1}(\bigcup_{i \in I} X_i) = \bigcup_{i \in I} f^{-1}(X_i)$

flat frigateBOT
ruby rapids
#

where $X_i, i \in I$ is any family of sets

flat frigateBOT
ruby rapids
#

likewise for intersections

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if you havent seen this yet its very easy to prove

lean otter
#

Ah, cool.

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Set theory?

ruby rapids
#

for direct images you have to be careful though

ruby rapids
#

set theory for me is more like cardinals, logic, forcing etc

lean otter
#

Right, right.

ruby rapids
lean otter
#

I've read a few books on ZF set theory.

#

It's fascinating.

lean otter
#

Now I have to figure out what a prebase is.

ruby rapids
lean otter
#

Also, what is the difference between a base/basis and a cover?

ruby rapids
#

where do you take the direct image of sets?

lean otter
ruby rapids
lean otter
#

I needed f-1(S) for S in B is open in X implies f is continuous.

ruby rapids
#

as i said, preimage behaves well for everything basically

ruby rapids
#

union, intersection, complement

lean otter
#

Thanks for the help with that! I did not know that.

ruby rapids
ruby rapids
#

no

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not necessarily

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but every base is an open cover

lean otter
#

Got it.

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I was trying to find the connection.

#

btw

#

I have an A- in topology now after the last quiz.

#

So I am improving! ๐Ÿ™‚

ruby rapids
#

nice

lean otter
#

Hmm, I can't find anything about a pre-basis.

#

On Wikipedia.

ruby rapids
#

yeah subbasis is the more common term i guess

#

or your book really means something else

lean otter
#

It wasn't from the book.

#

I would assume "pre"-basis is a more general structure that is not yet a basis.

#

So a base but without one or two properties?

#

oh

#

It's in my lecture notes. ๐Ÿ‘€

#

Okay, a "prebase" is a collection of subsets in X that covers X.

#

It is a subbase, according to the notes.

lean otter
ruby rapids
#

a collection of open sets $S = {U_i \mid i \in I}$ is a subbasis if $B = {\bigcap_{j=1}^n U_{i_j} \mid i_1,\dots,i_n \in I}$ is a basis. In other words, $S$ is a subbasis if every open set is the union of finite intersections of elements in $S$

flat frigateBOT
lean otter
#

Ah.

#

So all sets in S are open?

ruby rapids
#

yes

lean otter
#

Finite intersections?

ruby rapids
#

finite intersections of open sets are always open

#

or wdym

lean otter
#

Got it!

#

As in, all sets in S are finite intersections of open sets.

ruby rapids
#

i mean yes, but you probably confused something

lean otter
#

Oh?

ruby rapids
#

any open set is a finite intersection of open sets by just taking the "intersection" over a single element, namely that open set itself

lean otter
#

Ah, right.

#

But this sub-basis S contains entirely finite intersections of open sets and therefore all of its subsets are open, right?

#

That's what I was trying to confirm.

ruby rapids
#

the point is that S generates the topology in the sense that if S is a subbasis for a given topology, then that topology is the smallest topology on the given space that contains the S as open sets

#

because topologies must be closed under finite intersections and arbitrary unions

#

which are the operations with which you get every open set out of a subbasis by definition of the subbasis

#

its like a generating system in algebra

lean otter
#

That makes sense.

ruby rapids
#

i mean bases are also generating systems in that sense

#

but bases only need unions, not intersections

#

hence subbases tend to be smaller generating systems

lean otter
#

Hence "sub."

ruby rapids
#

the finite intersections come into play when you want to represent things that are not already in that subbasis

#

for example, the product topology on X x Y has a subbasis that consits of all sets U x Y and X x V where U open in X and V open in Y

#

if you just used unions, you generally couldnt represent sets like U x V, which are also open in that topology

#

but U x V = (X x V) n (U x Y)

lean otter
ruby rapids
lean otter
#

So if f-1(A) for A in S is open in X, then...

#

All open sets in Y for f: X --> Y are equal to the unions of finite intersections of sets A in S, which are open.

lean otter
#

Does that work?

#

I wrote it down more rigorously, but does the idea work?

ruby rapids
lean otter
#

Could I ask one more question?

#

I have another problem.

ruby rapids
#

ok

lean otter
#

Okay.

#

So:

Let X have the finite complement topology. Then X is compact and for all subsets of X, S is compact.

#

That's my last problem to prove.

#

I can't see how the finite complement topology matters for the rest.

ruby rapids
#

well not every space is compact

#

so it has to matter somehow xd

lean otter
#

It's compact if every open cover has a further subcover, yeah?

ruby rapids
#

generally note that in this topology (often also called the cofinite topology), open sets are very big

ruby rapids
#

any open cover is a subcover of itself

lean otter
#

Ohh

#

So showing every open cover is finite will suffice.

ruby rapids
#

but thats not true

#

at least not for inifinite spaces X

#

e.g. take the naturals with the cofinite topology

lean otter
#

But it has the finite complement topology.

ruby rapids
#

then the collection of all N \ {n} is an open cover

#

but this is not a finite set

lean otter
#

Hmm...

ruby rapids
#

you have to find a finite subcover

#

in this case, note that N \ {0} and N \ {1} already cover N

lean otter
#

It has something to do with the finite complement topology.

#

It just means that the closed sets are finite, right?

#

How does that help?

ruby rapids
#

bruh

#

i thought you were gonna complain that i basically just wrote the solution

lean otter
#

oh

ruby rapids
#

the proof generalizes

lean otter
ruby rapids
#

wat

lean otter
#

Then let {something} be an open set.

#

So X \ U = C is finite and covers X.

ruby rapids
#

a cover is a set of sets

lean otter
#

Yes...

#

Maybe the topology is a cover.

ruby rapids
#

in the above case i started with the open cover ${\mathbb{N} \setminus {n} \mid n \in \mathbb{N}}$

flat frigateBOT
ruby rapids
#

then i found the finite subcover ${\mathbb{N} \setminus {0}, \mathbb{N} \setminus {1}}$

flat frigateBOT
lean otter
#

lol what

ruby rapids
lean otter
#

Math is my name. This is not the math help channel, lol.

lusty grail
#

every time I submit it keeps saying it wrong when I type out the an-

#

Oh

#

OH

ruby rapids
#

m8 open your own help channel

lusty grail
#

SORRY

lean otter
#

XD

lusty grail
#

IM SO SORRY

lean otter
#

np lol

lean otter
#

What would take the place of {0}?

ruby rapids
#

well first try to do it for every open cover of N maybe

lean otter
#

Okay.

#

What is an open cover of N? xp

#

It just means each set in the cover is open in N?

ruby rapids
#

well we use the cofinite topology as in your exercise

lean otter
#

Right.

ruby rapids
#

so its a collection of sets with finite complement so that the union of all the sets is N

ruby rapids
#

that would be a finite open cover yes

#

but what is it for?

lean otter
#

I don't know...

ruby rapids
#

kek

#

ok so

#

we take an arbitrary open cover $C = {U_i \mid i \in I}$ of $\mathbb{N}$

flat frigateBOT
ruby rapids
#

each $U_i$ is open in $\mathbb{N}$

flat frigateBOT
ruby rapids
#

so that means $\mathbb{N} \setminus U_i$ is finite

flat frigateBOT
ruby rapids
#

now you have to find a finite subcover

lean otter
#

Ohhh

#

I see.

ruby rapids
#

i.e. $I_0 \subseteq I$ finite so that $\bigcup_{i \in I_0} U_i = \mathbb{N}$.

flat frigateBOT
lean otter
#

Something like U1 = even integers and U2 = odd integers would technically work.

ruby rapids
#

so we start with any $i \in I$ and note that $U_i$ is huge, i.e. it already almost covers $\mathbb{N}$, since $\mathbb{N} \setminus U_i$ is finite

lean otter
#

Where their union is N and the sets are finite in number.

flat frigateBOT
ruby rapids
ruby rapids
lean otter
ruby rapids
#

So first, the even intergers are not cofinite, since their complement is infinite, i.e. they are not open in N

lean otter
#

So for a cover {1, 2, 3}, a subcover is {1, 2}, for instance.

ruby rapids
lean otter
#

I just meant...

lean otter
#

They are technically finite in number.

#

I was just thinking, they're not covers / subcovers.

#

nvm

#

That wasn't my answer.

ruby rapids
#

now there isnt much left

lean otter
#

Right.

#

So Ui almost covers N...

ruby rapids
#

you have to cover the rest with finitely many other sets

lean otter
#

Take subsets of N/Ui?

#

We know N/Ui is finite and closed.

ruby rapids
#

yeah

#

its finite

#

so there you go

lean otter
#

But it's not a subcover.

ruby rapids
#

yes

#

but each element must be in one of the cover sets

#

since its a cover

ruby rapids
#

the U_j form a cover. so for every x in N \ U_i there is some U_(j_x) with x in U_(j_x)

lean otter
ruby rapids
#

what

lean otter
#

xp

#

I mean, all of the open sets together.

ruby rapids
#

i dont really understand what you want to do with that

lean otter
#

I'm just trying to process it.

ruby rapids
#

im so confused

lean otter
#

Me too.

ruby rapids
#

we want a subcover of the U_j

#

wo chose any U_i

#

that already covers N up to finitely many elements

lean otter
#

How is Ui a cover to begin with?

#

You said it "almost" covers N.

ruby rapids
#

each of the remaining elements is in some U_j

#

hence you have your finite subcover U_i,U_j_1, ... U_j_n

ruby rapids
lean otter
#

Ah.

#

Since C is a cover for X...

#

Anything left in X\Ui must be in the rest of the cover!

#

Right?

ruby rapids
#

basically yes, but what exactly do you mean by that

lean otter
#

Right.

#

So, then...

#

Any element x in X\Ui...

#

Must be in the rest of C = X\Ui is finite.

ruby rapids
#

wtf

#

C is a set of sets

lean otter
#

Right?

#

C\Ui is finite.

ruby rapids
#

X \ U_i is just a set

ruby rapids
lean otter
#

No?

ruby rapids
#

C is the cover

lean otter
#

Dang.

ruby rapids
#

$C = {U_j | j \in I}$

flat frigateBOT
lean otter
#

Yeah...

#

So take X\Ui for some Ui int he cover.

ruby rapids
#

you're confusing the space with the cover i think

ruby rapids
lean otter
#

Then an element x that is in X\Ui must be in the cover, right?

ruby rapids
#

things in the cover are open sets

#

not elements

lean otter
#

Because it's a cover.

ruby rapids
#

but x must be covered

lean otter
#

agh

ruby rapids
#

by some U_j

lean otter
#

Why?

#

oh

#

Is it because U1 U U2 U ... is open?

#

X = U1 U U2 U ...

#

X is the union of open sets.

ruby rapids
#

it has nothing to do with openness

lean otter
#

Okay?

ruby rapids
#

x in N \ U_i is in particular some element of N

#

C is a cover of N

#

this means the union of all the U_j is N

#

so since x in N

#

there is some U_j with x in U_j

lean otter
#

Right.

#

I follow that so far.

ruby rapids
#

ok but then thats it

lean otter
#

What is the finite subcover?

ruby rapids
#

we pick any old U_i and an enumeration {x_1,...,x_n} of N \ U_i

#

then for each x_k there is U_j_k with x_k in U_j_k

#

so the finite subcover is U_i,U_j_1,...U_j_n

lean otter
#

Ah.

covert forge
lean otter
#

So:

#
  1. C is a cover of X.
#
  1. Take X\Ui.
ruby rapids
#

and this generalizes traightforwardly to any subset of any space on which we put the cofinite topolgy

lean otter
#
  1. Let x be an element of X\Ui.
#

no

#
  1. Take {x1, x2, ..., xn} = X\Ui.
#

(Since X\Ui is finite).

#

Then...

#
  1. X\Ui is covered by some set of Uj's, each Uj containing some xi.
#

C. Then This set of Uj's is obviously a subcover of C and is finite because X\Ui is finite.

ruby rapids
#

yes

ruby rapids
#

just because you can choose a finite covering, doesnt mean you have to

#

so when you say its covered by some U_j that doesnt directly mean you pick a finite covering

#

or in you last step you just say "we can choose the covering of X \ U_i to be finite because X \U_i is fiinite"

#

instead of "it is finite"

lean otter
#

So I guess that makes sense.

#

Then I just need to prove that every subset of X is compact as well.

ruby rapids
#

its literally the same proof

lean otter
#

And I'll have survived another weekend of topology homework. ๐Ÿ˜ต

lean otter
#

Basically?

#

That it's a similar process?

ruby rapids
#

well

#

note that the subspace topology is also cofinite

lean otter
#

Right.

ruby rapids
#

and subsets are compact if they are compact as spaces with the subspace topology

#

so in this way you get the general case from the one you proved above

lean otter
#

So just say "the above proof applies to S with the induced topology from X, and if S is compact as a subspace of X it is compact as a subset of X as stated by Theorem 7.6 in the book."

ruby rapids
#

otherwise, what i meant above is that the same proof works because if X \ U_i is finite, then S \ U_i is finite for any subset S of X

ruby rapids
#

depending on how harsh they grade i would correct some formalities

lean otter
#

Okay.

ruby rapids
#

first you should state that you pick some arbitrary but specific j and then look at X \ U_j

lean otter
#

It's usually pretty chill as long as the answer is correct. I got a perfect score on a proof on a quiz just for drawing a picture. XD

#

And I often just draw pictures to prove something about sets on homework.

ruby rapids
#

next, you dont know what J looks like, so U_1 is not necessarily defined, you would have to pick indices i_1,..., i_n in I and look at U_i_1, ... U_i_n instead

#

also you switched from J to I midway

#

rest looks good

lean otter
#

I just meant U1 as in some arbitrary U that I ordered.

#

I don't think they'd take points off for a formality like that.

lean otter
#

.close

safe radishBOT
#
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lofty holly
safe radishBOT
lofty holly
#

how would i do this

jade gust
#

write everything as a base of 2

lean otter
#

write in the base of 2

lofty holly
#

please can you give an example

lean otter
#

what is another way to right 8 in terms of 2^x

lofty holly
#

3

lean otter
#

yep

#

do you know the exponent rules like power of a power

lofty holly
#

i think so

#

2 to the power of 3x

#

what next? <@&286206848099549185>

lean otter
#

What are the factors of 30?

lofty holly
#

1 30
2 15
3 10
5 6

lean otter
#

Yep.

#

So 30*2^3x can be simplified. How?

lofty holly
#

60 to the power of 4x

#

3x?

lean otter
lofty holly
#

okl

#

<@&286206848099549185> what should i do next

jade gust
#

Use a calculator sotrue

lofty holly
#

non calculator please

pulsar condor
lofty holly
#

ok

pulsar condor
#

but anyway, just simplify the RHS.

lean otter
#

Wait no

#

I'm stupid haha

pulsar condor
#

simplify the RHS, directed at the person getting help

lofty holly
#

"

jade gust
lofty holly
#

"advanced"

jade gust
#

I think you can continue from here

lean otter
#

๐Ÿ˜ญ

jade gust
#

factor 2^(52)

#

and yeah

#

I'll explain in a bit brb

lean otter
jade gust
#

I didn't even finish my solution

#

idk if that's even right sotrue

lean otter
#

Wait

#

No

pulsar condor
#

you both should stop posting answers/complete solution steps

#

(or attempting to)

jade gust
#

sheesh i'm a genius

#

okay so what i did was

#

I forgot what i did

#

Okay right so I've expressed 8^x and 4^(26) with a base of 2

#

I multiplied 30 to get rid of that fraction

#

So we have 30*2^(3x)=2^(56)-2^(52)

#

what

pulsar condor
#

equations don't become expressions

jade gust
#

and yeah i've written 30 as its factors, 2*15

#

wait

#

oh yeah

#

2*15*2^(3x) on the LHS

#

apply the exponent rule

#

a^b*a^c=a^(b+c)

pulsar condor
#

You could wait for them to actually be here and respond....

jade gust
#

they can read

pulsar condor
#

If you're just gonna give an entire solution

#

Which is already frowned on

jade gust
#

Well usually i type and they can read then they can ask

#

because people just tend to leave and i'm not waiting for them to respond

pulsar condor
#

If they leave, they don't need the help.

#

simple as

jade gust
#

@lofty holly dude are you here

#

why do people just leave on me

#

what have i done to deserve this

safe radishBOT
#

@lofty holly Has your question been resolved?

jade gust
#

bru

flat frigateBOT
jade gust
#

any questions just @ me

safe radishBOT
#
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โ€ข Type the command .close to free the channel when you're done.
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#
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Closed due to the original message being deleted

safe radishBOT
#
Available help channel!

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

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

eternal herald
#

What did I do wrong?

safe radishBOT
zinc crown
#

,w sqrt(3)/(sqrt(5)+1) - sqrt(3)/(sqrt(5) - 1)

flat frigateBOT
zinc crown
#

,w -sqrt(3)/2

zinc crown
#

nothing

#

ur answer is correct

#

@eternal herald

eternal herald
#

sorry

#

oh

#

OH GOD

#

HAHAHAHA

#

THE ANSWER WAS RIGHT THERE HOW DID I MISS IT IM LITERALLY BLIND

#

ITS B

#

BAHAHHA

#

IM SORRY

zinc crown
#

all g

#

use .close if u have no more questions

eternal herald
#

thanks!

#

.close

safe radishBOT
#
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โ€ข After 15 minutes, feel free to ping <@&286206848099549185>.
โ€ข Type the command .close to free the channel when you're done.
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narrow kraken
#

Hi

safe radishBOT
narrow kraken
#

When it says simplify for example for a I got 2^3.9 but do i give the exact value for that

#

same thing with b I got 15^2, do I leave it like that

safe radishBOT
#

@narrow kraken Has your question been resolved?

blissful gate
#

leave it like that

#

if they wanted exact value they would say "solve" or something

safe radishBOT
#
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โ€ข Type the command .close to free the channel when you're done.
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Read #โ“how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.

lean otter
safe radishBOT
lyric ingot
#

a(b+c) = ab + ac

#

That is the distributive property

#

So 3(3x+6) becomes 3(3x) + 3(6). Can you simplify that further?

#

@lean otter

lean otter
#

hmmm

lyric ingot
#

Let me know if what I said is confusing you

safe radishBOT
#

@lean otter Has your question been resolved?

safe radishBOT
#

@lean otter Has your question been resolved?

plucky elk
lyric ingot
#

Yes what riemann said, this is a good way to understand it. (I used this for exponent stuff before)

lean otter
#

ok

lyric ingot
#

For example 3(2+4)
Solve it normally using PEMDAS, which would be 3(6) which is just 18
Then use the distributive property,
3(2) + 3(4)
6 + 12
18
The answers are the exact same

safe radishBOT
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rare vale
#

What's the difference between variance and standard deviation?
I'm confused where they are used for

solid carbon
#

Sd = s

#

Variance = s^2

#

Simple

safe radishBOT
#

@rare vale Has your question been resolved?

#
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โ€ข Type the command .close to free the channel when you're done.
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safe radishBOT
novel atlas
#

lol

eternal herald
#

good luck

novel atlas
#

Where did i go wrong here

#

tx

#

<@&286206848099549185>

#

damn

#

any1

#

<@&286206848099549185>

safe radishBOT
#

@novel atlas Has your question been resolved?

safe radishBOT
#

@novel atlas Has your question been resolved?

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โ€ข Type the command .close to free the channel when you're done.
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vital zealot
#

can someone tell me how to do this one?

safe radishBOT
plucky elk
vital zealot
plucky elk
#

No not traingle

#

Triangle

vital zealot
#

yes

#

it was a typo

#

but triangle for what?

plucky elk
#

For sin A = 3/5

vital zealot
#

ohhh

plucky elk
#

Label the sides and then calculate the various trig functions for A

#

You know two already

vital zealot
#

various trig functions?

plucky elk
#

sec and tan are trig functions

vital zealot
#

yes

#

ohh ok

#

got it

#

thank you ๐Ÿ™‚

#

.close

safe radishBOT
#
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eternal herald
#

Can anyone explain why the answer is the eighth root of 128?

safe radishBOT
#

Please don't occupy multiple help channels.

eternal herald
#

but i have a different question...

worthy hemlock
eternal herald
#

oh

worthy hemlock
#

So you should go ahead and either close this channel or the other one you have

eternal herald
#

.close

safe radishBOT
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lean otter
#

help i keep getting 140 but the answer is 153 question : (22)/(5)+(13)/(4)

arctic osprey
#

how is the question formatted

#

because as i see it this is (22/5)+(13/4)

lean otter
#

yeah thats what i got

#

and i keep getting 140 but the answer on calculator says 153

arctic osprey
#

wdym 140

lean otter
#

the answer is 140 over 20

arctic osprey
#

mixed fractions

#

show work

lean otter
#

ya im re learning them for a test

#

ok

#

hold on

#

i re did it

#

but im going on my phone

arctic osprey
#

can i see what you tried

lean otter
#

to show the work

#

yeah

#

i cant find the math help message thing

#

so ima dm u it

arctic osprey
#

just put it here

lean otter
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i cant im on pc i can open this message up but

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phone i cant

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there

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do you see it ?

arctic osprey
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you multiplied 13 and 5 incorrectly

lean otter
#

fr?

arctic osprey
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you did 13*4

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not 13*5

lean otter
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๐Ÿ’€

arctic osprey
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everything else looks right

lean otter
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ohhhh my god bro

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ya u right

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i type on the calculator

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13x4

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bruh this why i dont do math practice at night

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im too sleepy

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thanks big dawg'

plucky elk
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.close if you're done

lean otter
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.close

safe radishBOT
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Channel closed

Closed by @open mica

Use .reopen if this was a mistake.

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karmic monolith
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Hi, I'm trying to do this problem but I really have no idea where to start, any guidance?

fair dagger
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This means that we are given the tanget of something and we call it x

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and we are looking for the sine instead.

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So I would try writting down the useful equations defining this

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and trying to rearrange.

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tan(y) = sin(y)/cos(y)

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and

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(sin(y))ยฒ + (cos(y))ยฒ = 1

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We can use these to accomplish the goal.

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@karmic monolith Does this help?

karmic monolith
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Sorry, was afk, let me read.

fair dagger
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x = tan(y)

karmic monolith
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Since it's inverse tangent, how would that work?

fair dagger
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If we find some expression of the style

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sin(y) = f(tan(y)) using the above formulae

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then we can conclude that sin(tan^-1(x)) = f(x)

karmic monolith
fair dagger
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something we are trying to figure out rn

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We want to express sin in terms of tan.

karmic monolith
fair dagger
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yeah

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the issue though is that cos isn't known yet

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we need to elimate that

karmic monolith
fair dagger
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maybe ๐Ÿ™‚

karmic monolith
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Ok, so then we'd have sin(y) = (-sin(y)ยฒ + 1) * tan(y) if I did that right

fair dagger
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I think you lost a square root somewhere

karmic monolith
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Oops you're right

fair dagger
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because cos was squared before

karmic monolith
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sin(y) = -sqrt(sin(y)ยฒ + 1) * tan(y)

fair dagger
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there is also an annouance with the sign but let's ignore that for now

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it could be -sqrt

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Now we "just" need to solve this for sin and we are done

karmic monolith
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Do you mean for tan? Isn't it already solved for sin?

fair dagger
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sin appears at both sides though

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you can't compute the left side like this

karmic monolith
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Oh right.

fair dagger
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if you are given the tan

karmic monolith
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Ok I've gotten it to this, not quite sure how to proceed though.

fair dagger
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We somehow need to recombine the sin eventually

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to this end one large hurdle is the square root

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so I would suggest to square the original equation at both sides

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eliminating the square root

karmic monolith
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Alright.

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I think it would be this now

fair dagger
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yeah

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tbh I think the fraction was just not helpful in the end

karmic monolith
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No?

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Ohhh its not multiplication on the bottom

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oops

fair dagger
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no, you would need to divide the 1

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making it no better

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I think we should instead eliminate the fraction

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so that it becomes a quadratic equation

karmic monolith
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Also I do have the answer for this problem, I've just been lost on how to solve it

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Wait... how would I make it a quadratic equation?

fair dagger
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yep

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sin(y) is the unknown in this case

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it's a quadratic equation in sin(y)

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you can bring it in cannonical form

karmic monolith
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What's that?

fair dagger
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a sin(y)ยฒ + b sin(y) + c = 0

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with a b and c known constants only involving the tan(y)

karmic monolith
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I'm not really understanding, how do we turn the equation into that form?

fair dagger
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Hint: Distributive law

karmic monolith
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Ok, I'm here with distributive

fair dagger
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Now you can identify a, b and c and use the standard quadratic formula

karmic monolith
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So would A be -tan(y)^2)? And then b 1 and c 0?

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Or do I need to move that other sin(y) to the other side