#help-19
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Prime Minister
write $sin(\frac{11\pi}{6})$ as $sin(\frac{12\pi}{6}-\frac{\pi}{6})$
Prime Minister
sine is positive only in the first and second quadrants
12pi/6 becomes 2pi and it goes bazoonk because its a full circle and we dont count full circles because youre essentially back where you came from
so you remain with $sin(-\frac{\pi}{6})$
Prime Minister
oh 😭
which to say is the same as $-sin(\frac{\pi}{6})$
Prime Minister
right right
sorry yapped too hard
ok wait let me try the second one
then u can keep yapping
if i get it wrong
okay wait i'm trying to draw it but like
where do i make the right triangle
its cos60 degrees
htink of π as 180, then you just do simple division and youre gucci
except like the first one where its a little quirky
wait what do you mean do division
yee tan 180 that is a solid zero
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i simply dont get the sentence
and the thing in general
it says sum of the first n terms is equal to the quadratic expression
try finding sum of first terms
8 and 2 ?
also consider when n = 1 to find first value
no
whats formula for sum of first n terms in arithmetic progression
answer pwease :3
if u don't know it, then this problem might be too advanced for u
this math software is poopoo
!noans
The purpose of this server is to help you learn, not to hand out answers. Do not ask someone to give you the answer directly.
yea u have to have an understanding of arithemtic sequences for this
try finding sum of first terms
my brain is not at its fullest since its 1 am where i am
3 am here
a) hint: if you take n = 1, then what happens?
it works fine
b) use the formula, S_n = n/2 * (2a + (n-1)d)
and plug in what a is equal to (because a is the initial value), which you get from part a)
you have a simple quadratic in d
if u don't have a good understanding of arithmetic sequence, as well as algebra then this problem is probably out of ur reach and its not gonna be helpful to u
its not that i dont understand algebra its easy but the problem is that a english isnt my first language and b my brain is not at its smartest since i was in winter holidays
ok, an arithmetic sequence is a sequence like 3, 5, 7, 9, ...
yeah
where the difference between each term is a cosntant (typically d)
mhm
the formula for the sum of the first n terms of an arithmetic sequence
can be derived as following:
oooooh
sum = # of terms multiplied by avg. value of term
let # of terms be n, common difference be d, and first term be a
the # of terms is just n
and the avg. value of term is equal to (first term + last term) / 2 because it is an arithmetic sequence
first term is a, last term is a + (n-1) d
.close i will do it tomorrow with a bright head
so the avg. value of term is (2a + (n-1)d) / 2
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Can someone help check my work
I tried to find a “better integral”
For the gamma function
Someone tell me how much I messed up
@old whale Has your question been resolved?
<@&286206848099549185>
@old whale Has your question been resolved?
<@&286206848099549185>
@old whale Has your question been resolved?
what are you even trying to do?
<@&286206848099549185>
refer to what @tall veldt said
this kinda hurting my brain
gamma function?
@old whale Has your question been resolved?
<@&286206848099549185>
I wanted to find another way to “generalize” the gamma function. I’m not sure if it is correct though.
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I was unsure as to how to do A here, so I checked the mark scheme. After checking it, i'm still unsure as to how to factorise from
3(log3p)^2 -8log3p + 4 = 0 into the next line, could someone explain?
i don't get where the -8 coefficient to the log went
have you factorised quadratic equations before?
would you be able to factorise the similar expression:
$$3x^2 - 8x + 4$$
ℝαμΩℕωⅤ
yes i have,
(3x-2)(x-2)
i just confused with the 3 coefficient out the bracket and then it goes inside, and where the -8 coefficient to the log went
ℝαμΩℕωⅤ
$3\underbrace{(\log_3p)^2}{x^2} - 8\underbrace{\log_3p}{x} + 4$
ℝαμΩℕωⅤ
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if {$x$} denotes the fractional part function, find {$\frac{3^2n}{8}$} , where n is a ntural number
*fractional part of 3^n/8
I did get 1/8 by trial and error
but how would I get a result more rigourosly
You would look at 3^n mod 8
well if n = 1 then 3^n/8 is 3/8 and the fractional part of 3/8 is not 1/8 so uh
I meant 3/8 my bad
well if n = 2 then 3^n/8 is 9/8 and the fractional part of 9/8 is not 3/8 so uh
It depends on whether n is even or odd
Why am. I here
yeah
ooh, then it's 9^n, right?
(3^(2n) is written 3^{2n} in latex)
$\left{\frac{3^{2n}}{8}\right}$
is there any way without modular arithmatic? modular arithmatic isn't in my syllabus
Jelle
yes, this is my question. TYSm
i guess induction on n?
I mean, modular arithmetic is essentialy looking at remainders
so you can prove something about the remainder after division by 8?
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Hey guys, I wanna ask for help:D
basically, my question is
f(x) = ax^2 + bx + c
f(x) = x^2 + 2x + 5
I did is
y - 5 = x^2 + 2x + _
then
[(1/2) (b)]^2
[(1/2) (2)]^2
[(2/2)]^2
(1)^2
then
y - 5= x^2 + 2x + 1
and i did
y - 5 = (x+1)^2
then i tranposed 5
and got f(x)= (x+1)^2 - 5
and my a,h,k are 1,1,-5
(its confusing but i can make it on paint)
please do
whats the question
uh
yea idk
hold up
its my assignment, but i dont get it , but i'll show the picture of the question
yeah
ohhh
do you know this?
yea
why 4?
oh
oh yea
what we did in right side, we do in left side
i forgot about that
so the a h and k are 1,1,4
?
I also have another question, cause i'm confused about it and i cant complete the square
@twilit flax Has your question been resolved?
the coefficient of x^2 should be 1
what?
yea
i know
but i have another question
cause i cant solve this and i dont know how to do it
can you show that
basically the question is
f(x) = 2x^2 + 5x + 4
i got to the part where i got in
y - 4 = 2x^2 + 5x
I don't know how i'm gonna factor out 4
oh wait
i dont get anything
he didnt ask to complete the square
yes
forget that
its until to complete the square
i was thinking to get like
2(x^2 + 5/2x) + 2
or smth
you were trying to complete the square right?
its done like this
what is that
this term is (x+5/4) ^ 2
but why 4?
i did the same thing
like uh
2(x^2 + [5/2]x + (5/4)^2 ) + 4 - 2(5/4)^2
damn
steps?
i was thinking uh since equation was 2, wouldnt be 2 added to left side or no?
i first made the coefficient of x^2 to be 1
and not 2
this step
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but how do you get the 5/4 as the final answer
yeah im telling you
with other stuff like that
now we add and subtract the ** half of the square of the coefficient**
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oh yea
i dont know how that works
how do you do tihs?
they never taught us that, or i just forgot it
okay
okay
its literally
oh my god why am i acting dumb
1/5(x+0)^2 + 1/5
same way
oh wait
how about this
f(x) = 4x^2 + 5x - 8
i did was uh
y + 8 = 4x^2 + 5
then i need to factor out 4 again
y + 8 4(x^2 + 5/4
and then complete the square
is it just gonna be like that
good
Alright
its not
so it doesnt make a difference
i dont which is which
4x^2 + 5x - 8 right
yup?
whAt
uh
dont
you might be thinking why did I do this right?
yea?
that's because
no i'm just confused where did you multiply to get 2
I re-wrote the whole equation
have a look at it again
the 2nd equation is same as the 1st
oh
I'll do it in this way
its in the question...
Exactly
take the 8 to the right hand side
isnt that -8?
why
cause you can't factor it anymore i guess?
am i right
i am
oh
understood?
yeap
Nice!
the reason why I did that was
this thing
this part is (x + 5/4) ^ 2
then
so h is -5/4
where 2?
forget that
the solution starts from here
aight
understood?
how do you get the answer without completing the square
aight
you need practise
i can but i dont know where to start
to the point where you don't need pen
what is the questions?
i dont even make my own solution i just go with my brain
he wants to represent the quadratic equation in the form of
a(x-h)^2 + k
ah
basically completing square
yeah
so yeah
there are videos on yt
yeah that is the vertex form?
what
ah
how does this change anything?
just learn method of completing square
aight
i dont know either
i just said it
@iron grotto
wait
hi
ok
uh
this
f(x) = 3x^2 - 4x - 7
will it be the exact thing
like
y + 7 = 3(x -4/3)^2 smth like that
aight
thats not how u complete the square
.
see this.
i cant complete the square when i cant factor it thats why
aight start from beginning
.
Step-by-Step Technique on How To Solve Quadratic Equations by Completing the Square. By PreMath.com
we want to first pull out the 3
huh
y = 3(x^2-4/3x) - 7
dont try to do it all in 1 step
so pull out the 3 from both terms with x
then
then
to complete the square take the 2nd term and half it
how can i half 4/3
half the numerator and if u cant then double the denominator
so in this case its 2/3
now ignore the x
now this becomes y = 3(x-2/3)^2 - 7
but you have to remember that when you complete the sqaure you have actually added an extra term
and that is?
because when you expand (x-2/3)^2 you get x^2-4/3x+4/9
ah
the 4/9 was added so to account for that we have to subtract it to stay even
so now we have y = 3(x-2/3)^2 - 7 - 4/9
then what do you do on the last constant/s
common denominator then you could subtract them
oh
so make the -7 into -63/9 -4/9
which becomes -67/9
so we should have y = 3(x-2/3)^2 - 67/9
then finally we can add it to the other side
y + 67/9 = 3(x-2/3)^2
then subtract 67/9?
oh did you want it all on one side
this would be it with all on 1 side
oh
wait
me and zerome did this problem
im not sure if its still correct 🕴️
its this
4x^2 + 5x - 8
u understood?
on this part i did
try this problem for yourself
alright
what would be the first step?
hmm we want to factorise first
yeah
y + 8 = 4(x^2 + 5/4x) , just fixing it up
yeah
half?
yep
then what would it be
well we cant half 5 so we will have to double 4, 5/8
hmm its going to be complicated but we have to do this all in one step
wait
no..
i have a question and its not related to this
aight
uh back to this
how does it work
so when we figure out the half
hmm
we can then complete the square by using the half, y + 8 = 4(x + 5/8)^2, but remember there is an extra term that we added
to find that extra term, we have to square the half number we worked out before
(5/8)^2
= 25/64
and then we have to subtract that
y + 8 = 4(x + 5/8)^2 - 25/64
so we used to have (x^2+5/4x) in the brackets right?
when we complete the square we halfed the 2nd term to get (x+5/8)^2
yeah but why is the 25/64 negative
but when we expand that we get (x+5/8)^2 = x^2+5/4x+25/64
ah
see that extra 25/64 that we added
yup
to account for adding that, we have to subtract 25/64 to keep it equal
is the -25/64 negative or no?
x^2+5/4x+25/64 doesnt equal x^2+5/4x because the left side has an extra 25/64
its back to 5/4?
no that is just what we get when we expand (x+5/8)^2
its this
but if we want it all on one side we are going to have to subtract 8
y = 4(x + 5/8)^2 - 25/64 - 8
yeah
wait
?
what's the lcd gonna be
i was just thinking 25 or smth cause of 8
imaginary 1 skillz
well look at the denominators
-25/64 has a denominator of 64
and 8 has a denominator of 1
then 64
yeah
8/1 and we want a denominator of 64, we have to times both sides of the fraction by 64 to make it equal
huh
a
if we want 1/2 to have a denominator of 4 we have to times both sides by 2
so we have 2/4
in here?
-25/64 already has a denominator of 64
so what about the 8
well 8 = 8/1
not yet because you made the fraction wrong
oh
8/64 doesnt equal 8/1
because you have only multiplied the denominator
you have to also multiply the numerator by 64
Galaxy
the 25 is gone
yeah we arent worrying about the 25 because we still need 8 to have the same denominator
and that is
64
we want -25 and -8 to have the same denominator of 64
-25 alreadu has a denominator of 64
so there is only 1 number left that doesnt have a denominator of 64
then
8
no
look at this
u did this wrong because 8/1 is not equal to 8/64
they are completely different numbers
8/64 is equal to 1/8
and therefor you would be doing -25/64 -1/8
but that isnt what we are looking for
we are looking for -25/64-8/1
im just thinking of reciprocal tbh
whaT
what is confusing?
why 5/10
im just picking a random number since i feell like you arent getting this
im weak at fractions thats why
ok so i will now explain
alright
then
in order to get to 40 we have to multiply 10 by 4
but
to keep the fraction equal, you must also multiply the top by 4
5/10 = 20/40
are u asking a question or are you wanting me to do it?
yes
then x64?
yes
where did it go
.
yes
are you saying -25/64 - 512/64 or something else
yeah
yeah but its not fully simplified
-537 / 64?
what can we do with 2 numbers of the same denominators?
yes
yeah
yeah
wait
try a simple one f(x) = 2x^2+4x+7 to solidate this
best to start slow because we are mixing up some steps
alright
first step?
no its to factorise
right but what is 4/2?
y - 7 = 2(x^2 + 2x)
yeah
and uhhhhh
so next step?
yeah
wait
oh ya
(1)^2 = 1
mb
then what i did to right side
im gonna do it on left side too
y - 7 = 2(x^2 + 2x + 1)
something's wrong
oh right i have forgotten i step
i need to add the 2 on the left side
yeah
right?
yeah
yeah
wait
how do i do uhhhh
when the coefficient is like
negative
like
-3x^2 -9x + 11
ok
im still confused on that problem
oh yea
but
its still 11?
we're not gonna uhh
add
add -3 in left side
hold up
wait
no we havent gotten to that yet
what are we adding?
hmm i think you are mixing some things up
i will provide the solution
f(x) = -3x^2 -9x + 11
first step factorise out -3
f(x) = -3(x^2 +3x) + 11
what numbers specifically?
it's not x^2 + 3x^2
?
i did this problem and it's f(x) = 7x^2
and i answered f(x) = 7(x - 0)^2 + 0
yeah thats correct
?
vertex form is a(x-h)^2+k right
yep
,.
continuing from this
aight
not exactly ur still missing things
y - 7 = (-x^2 - 4 - 4)
-1"?
y=-(x^2+4x)+7
yeah because if we want to get the form a(x-h)^2+k
if we dont factor out that negative from the start
we will have
a(-x+h)^2+k
which they are the same
but it depends on what ur teacher is looking for
when ur at this step we want to look at the 4x and find [1/2(b)]^2
which is [1/2(4)]^2 = 2^2 = 4
isnt it this
no because of multiply things
oh
secondly its not -4 at the end
right
so
y-7=(-x^2-4x+4)
oh ya
so you also have to add 4 to the left
-7+4
aight
everytime you see a negative sign you can think of it as -1
-2 = -1(2)
so --2 = (-1)(-1)(2)
= 2
aight
wait
im tryna work on this problem
3x^2 + 5x = 10
basically i got uh
y - 10 = 3(x^2 + 5/3)
oh wait
ok in this situation you have to treat it differently
3x^2 + 5x = 10 we cant just add y since we dont have f(x)
aaaaa
with a question like this we are looking for an answer
im trying to solve this
but im stuck at 5/3 and im thinking to double the denominator like that
different approach to this question
3x^2 + 5x = 10
we dont have to complete the square
oh is this the question?
double denominator i guess
yeah
oops
yeah
but we just added 3(25/36) to the right side
add something in outside
so we have to also add it to the left
y - 10 + 3(25/36) = 3(x^2 + 5/3x + 25/36)
we can simplify it to y - 10 + 25/12 = 3(x^2 + 5/3x + 25/36)
then we can also complete the square
y - 10 + 25/12 = 3(x+5/6)^2
then common denominators and so on
its 3 am here, so im going to bed
its back to 10/1 stuff like that
correcy
@twilit flax Has your question been resolved?
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how do i solve b)? dont mind the language it is swedish. a) asked for det derivitive of f. But i cant figure out what f(theta(t)) is.
there's no mention of theta(t) before ?
i guess they assume that theta(t) is the unite function
i think that is what is called but when t <0 it is 0 and t > 0 it is 1.
OH
I guess that's it yes
i figured it out
I don't know what i was thinking but it is only f(1) they ask for
i feel dumb lol, but thanks anyways!
hmmm but it shouldn't matter in this case right?=
the answer is just 4*theta(t) then or?
f(theta(t))= 4theta(t) yea
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the curve y=ax^2+bx+c has a tangent y=x in origo. the curve has a second tangent for the line y=2x-3. decide what the constants a, b, c are.
i managed to understand that since y=x c would be 0. but i couldn't find out the answer to b or a, so i checked the answers since i'm studying at home and don't have a teacher here. and the answer sheet says that the first step in finding out what b is that we know that y'(0)=1. but i did not know that. how do i find that out.
also sorry if i'm not using the wrong math words. english is my second language and i don't know the exact translation to every word.
"has a tangent y=x at the origin" means y'(0) = 1
what? why?
also this: "i managed to understand that since y=x c would be 0" is incorrect