#precalculus

1 messages · Page 197 of 1

uncut mulch
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chain rule. and/or you can factor out the 1/3 first.

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it will involve ln, but you didn't do it properly

undone pawn
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you have written $\int \frac{1}{3x} dx = \ln(3x) + c$

obsidian monolithBOT
undone pawn
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if that is true

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check if $\frac{d(\ln(3x))}{dx} = \frac{1}{3x}$

obsidian monolithBOT
undone pawn
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if not, you're wrong

viscid thistle
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Don't mean to disrupt the discussion, I'm just wondering about something. Is this being taught in a precalc class somewhere in the world? The schools I'm familiar only cover this in calc classes.

serene heath
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no this is calculus

viscid thistle
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Ah ok. I wasn't sure if the school system had moved on. Because I have seen way too much calculus in this text channel

languid crane
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^ same

sharp quest
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if i have $log_5 6$

obsidian monolithBOT
sharp quest
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can i just switch 6 and 5

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and it'd be equal

viscid thistle
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No

sharp quest
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how does

willow bear
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how does what

sharp quest
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$\frac{1}{\frac{log_5 5}{log_5 6}}$

obsidian monolithBOT
viscid thistle
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$log_5 6$= $log 6$ / $log 5$ which doesn't equal $log 5$ / $log 6$

obsidian monolithBOT
sharp quest
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ya i forgot about the 1

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over everything

willow bear
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OH MY GOD THAT IS SUCH HORRENDOUS LATEX MY EYES ARE LITERALLY BURNING

viscid thistle
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:) sry am on phone

willow bear
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that

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doesn't excuse the GROSS OVERABUNDANCE OF DOLLAR SIGNS

viscid thistle
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Haha true haha

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I don't have experience with the latex bot

sharp quest
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ok so how does this

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$\frac{1}{\frac{log_5 5}{log_5 6}}$

obsidian monolithBOT
sharp quest
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=

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$log_5 6$

obsidian monolithBOT
willow bear
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$\frac{1}{\frac{x}{y}} = \frac{y}{x}$ that's how

obsidian monolithBOT
willow bear
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and $\log_5(5) = 1$

obsidian monolithBOT
viscid thistle
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Love how fast u wrote the first line

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Almost like u had it on copy pasta

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✓✓✓

sharp quest
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$\frac{log_5 5}{log_5 6}$

obsidian monolithBOT
sharp quest
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wait what happens here

willow bear
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$\frac{1}{\frac{x}{y}} = \frac{y}{x}$

obsidian monolithBOT
willow bear
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$\frac{1}{\frac{\log_5(5)}{\log_5(6)}} = \frac{\log_5(6)}{\log_5(5)}$

sharp quest
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dude did you type that only after i messaged

obsidian monolithBOT
sharp quest
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wtf

willow bear
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do you understand this or not?

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also, do not call me dude.

sharp quest
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ya i understand that part

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but what do you do next

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to get log_5 6

viscid thistle
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and $\log_5(5) = 1$

obsidian monolithBOT
sharp quest
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ohhh

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sorry didnt know that was what you meant earlier ann

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thanks

willow bear
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you're so very welcome.

sharp quest
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$\frac{1}{\frac{log_c a}{log_c b}}$

obsidian monolithBOT
sharp quest
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so if i have this

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it always becomes

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$log_b a$

obsidian monolithBOT
willow bear
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no

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$\frac{1}{\frac{\log_c(a)}{\log_c(b)}} = \frac{\log_c(b)}{\log_c(a)} = \log_a(b)$

obsidian monolithBOT
sharp quest
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oh alright thanks

pale bison
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is it log(x+1) or log(x) + 1?

serene heath
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probably the latter

pale bison
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well that makes stuff a lot easier...

night wigeon
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do i just square root the right and left side?

patent beacon
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Nuu

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This is seperable

night wigeon
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wdym

patent beacon
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You rearrange to write
y dy/dx = -3x² - 4x - 8

Then integrate both sides:
1/2 y² = -x³ - 2x² - 8x

night wigeon
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yea thats what i did

stuck lark
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what happened here? did you multiply by 2 in the bottom step?

patent beacon
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Oh yeah don't be like me and forget the +C

night wigeon
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ya i did

stuck lark
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then the coeffs of x^2 and x are off

patent beacon
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Mb I didn't see your work above

night wigeon
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oh your right

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what do i do after i get y^2 =

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do i square root both sides?

stuck lark
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y^2=... is really an implicitly defined curve, y isn't a function of x. but if we take sqrt of both sides and "cut" the curve at a specific point, we can make y an explicitly defined function of x

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algebra wise yea, just sqrt and pick the "cut" that satisfies y(0)=2

night wigeon
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i got y = -2x^3/2-4x-16x^-1+2

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easier view

stuck lark
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show me your work after y^2/2=...+C

night wigeon
stuck lark
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,rotate 45

obsidian monolithBOT
night wigeon
stuck lark
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yes

night wigeon
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the answer still says im wrong

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where did i go wrong

stuck lark
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sqrt(x) is not x^(-1)

night wigeon
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oh its 1/2

stuck lark
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also

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sqrt doesn't distribute

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sqrt(a+b) != sqrt(a)+sqrt(b)

night wigeon
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but if you square root everything

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doesnt it all get affected

stuck lark
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that doesn't refute "sqrt(a+b) != sqrt(a)+sqrt(b)"

night wigeon
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how does that come into this question, isnt it only sqrt(y)

patent beacon
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You're taking the square root of each term individually. That's a no-no

night wigeon
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ohh

stuck lark
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freshman's dream strikes again, with n=1/2

night wigeon
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ty that was the right answer

stuck lark
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np

obsidian monolithBOT
night wigeon
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how would i solve this

earnest nymph
stuck lark
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,rccw

obsidian monolithBOT
stuck lark
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similar to the last one, this is a separable equation, meaning the x and t stuff can be moved to separate sides and integrated

night wigeon
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ive found the value for the constant c

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altho im confused because i dont know what x(T) = wants me to enter as my answer

stuck lark
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isolate x(t)

night wigeon
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i dont have a x(t)

stuck lark
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isolate x

night wigeon
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done

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and then set t to zero?

obsidian monolithBOT
stuck lark
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we have the initial condition x(0)=0 so yes plug that in

solemn sluice
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Could someone help me with 3!

lofty geyser
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Does anyone do personal math tutoring

quasi meadow
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@solemn sluice you probably want to simplify the left side of the equation you are trying to prove so solve for c in terms of a with law of sines

solemn sluice
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Mmm ok tyvm

trim fable
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hi

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can someone help me

steep yarrow
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Hello I’m from Canada and need help with this log question

sturdy haven
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How do you multiply exponents with the same base and same power

steep yarrow
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You just add the powers?

sturdy haven
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But 6x^2 x 6x^2 = (6x^2)^2 correct?

steep yarrow
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Yea aka 6^4

sturdy haven
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Do you distribute the exponent?

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6^2x^4

steep yarrow
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Idk what you mean bruh

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To answer your original question you just add the powers if they have the same base when multiplying

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ie. 5^2 * 5^3 = 3125

2+3 =5

5^5= 3125

willow bear
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$6x^2 \cdot 6x^2 \neq 6^4$

obsidian monolithBOT
willow bear
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@sturdy haven do not use x for multiplication especially when you have a variable called x

fluid shore
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@trim fable you good with that question?

still yew
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So, I dont know why but I am having trouble grasping law of cosines...first off, can when solving a triangle, result to 2 solutions if using the law?

willow bear
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depends on what you're finding

still yew
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For example, a = 2, b = 5, C = 50 degrees

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SAS

willow bear
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if you're finding an angle from three sides, or a side from the other two and the angle between them, then no, there is never any ambiguity

still yew
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Nvm, SSA

willow bear
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no, you were right the first time. this is SAS. angle C is opposite side c.

still yew
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Ah

trim fable
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@fluid shore nope

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can u help

fluid shore
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Sure

trim fable
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yay

fluid shore
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So have you added both of them

willow bear
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what is the question again

fluid shore
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What have you gotten so far?

trim fable
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oh well

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i did something weird

fluid shore
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You’re just adding two quadratic expressions together

still yew
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First off. Does it give m or nM

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?*

trim fable
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oh i did them separately like

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i have 4 equations

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h(1) for

willow bear
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you have FOUR equations???

trim fable
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f(x), g(x)

fluid shore
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:/

still yew
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Why 4?

trim fable
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no then

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i made it into

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2

still yew
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You need 1

fluid shore
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Ann wait

trim fable
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i broke it down

fluid shore
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Tell us first what you have done first

still yew
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Oh

trim fable
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ok

fluid shore
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Show your working, star

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Like, the piece of paper on which you wrote stuff down

trim fable
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h(1)= 1^1 - n(1) +5 h(1) = m(1)^2 + 1 -3 h(-2) = -2^2 -n (-2) +5 h(-2)= m(-2)^2 + -2 +3
= 1 - n +5 = m-2 = 2n+9 = 4m +1
= -n + 6

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then I did

willow bear
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this is impossible to read on mobile.

trim fable
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2n+9 = -n +6 4m+1=m-2
n=-1 m=-1

fluid shore
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Star, write things down on a piece of paper

trim fable
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LOL idk what i did

willow bear
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what is h(x)?

fluid shore
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It’ll be clearer that way

trim fable
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i cant take a pic of it tho

willow bear
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also if you don't know what you did then chances are you did it wrong

trim fable
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thats the problem LOL

fluid shore
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Exactly

trim fable
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ik what i did but

fluid shore
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Okay let’s start from the beginning

trim fable
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ok

fluid shore
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What’s h(x)?

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Write it out

trim fable
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f(x) +g(x)

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oh..

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i sub it in one at a time LOL

willow bear
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no, write it out explicitly. an explicit formula.

trim fable
#

OHHHHH

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OMG NO

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i cant use this to do it

willow bear
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write out what h(x) is explicitly.

trim fable
#

let me try brb

fluid shore
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Mmh

trim fable
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ok

fluid shore
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So what have ya come up with?

trim fable
#

umm

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the wrong answer

fluid shore
willow bear
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have you written out h(x) explicitly?

trim fable
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one secccc

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lets see

willow bear
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have you or have you not written out h(x) explicitly?

trim fable
#

:C

fluid shore
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Star, write it out explicitly

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There’s nothing wrong with following the direction we’ve given

trim fable
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ik

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i wanted to see if i could do it but ok

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ill try

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i just didn't

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wanna erase lol

fluid shore
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Lmao

willow bear
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if you didn't do what you were told to do, say so outright rather than stalling as you just did.

trim fable
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ok so

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for h(1) i got

willow bear
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NO!

trim fable
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-n+m+4=0

willow bear
#

write out
h(x)
explicitly!

trim fable
#

what do u mean

willow bear
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h(x) = (x^2 - nx + 5) + (mx^2 + x - 3) = ???

trim fable
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oh thats what u mean

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like without subbing?

willow bear
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(m+1)x^2 + (-n+1)x + 2 no bueno????????

trim fable
#

bueno?

willow bear
trim fable
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oh

willow bear
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why couldn't you write this out. why did it take me and abhi so many times.

trim fable
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huh

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well im still gettinf

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-n+m+4=0

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for one of them

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is that right

willow bear
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how did you get that

trim fable
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u know

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maybe im too tired rn

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i need sleep

willow bear
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okay

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then get some sleep

trim fable
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i do get what u mean tho

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im just forcing myself up to do it

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well goodnight thanks

fluid shore
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Try it when you’re more awake

viscid thistle
#

can anyone help with proof by mathematical induction? i got stuck on inductive step... it looks like this: 1 + 2(1/2) + 3(1/2)^2 + 4(1/2)^3 + ... + n(1/2)^n-1 = 4 - ((n+2) / (2^n-1))

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first you assume that n=k

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and then i got stuck on n=k+1

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<@&286206848099549185>

blissful wadi
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who's wrong ?

willow bear
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you

blissful wadi
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oh okay

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btw what i did wrong ?

willow bear
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generally $\int_a^b |f(x)| \dd{x} \neq \absv{\int_a^b f(x) \dd{x}}$

obsidian monolithBOT
blissful wadi
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oh

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so how can i use abs(x^2-x) ?

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i mean integrate it*

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is there any methode for the absolute value ?

willow bear
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i mean you tried splitting the integral up based on the sign of x^2 - x

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which is good

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you just didn't do it properly

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x^2 - x is less than zero iff x ∈ ]0,1[

blissful wadi
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ohhh

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yeaaah

willow bear
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so you'd be splitting this up as $\int_{-1}^0 + \int_0^1 + \int_1^2$

obsidian monolithBOT
blissful wadi
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yeah true i forgot about ]0,1[

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thankss

trim fable
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hi

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@fluid shore hey are u there 😛

fluid shore
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Now I am

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Lel sorry, just woke up

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@trim fable

harsh cipher
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question

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shouldnt it be y= -2sin x +0.5?

noble sundial
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@harsh cipher yup

harsh cipher
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ok thanks

trim fable
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@fluid shore hi 😛

fluid shore
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🙂

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Do you have a question? Are you all good with yesterday’s problem? @trim fable

trim fable
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oh no

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i wanted to ask u that before

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I realized what i was doing wrong

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but i dont understand what im supposed to do

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i have a test tom im stressed :c

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so what i was doing was

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h(x)= f(x) + g(x) and i subbed in 1 into the equation and solved but then

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instead u add them like uh.. in a way idk how to

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@fluid shore

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like how would u add ( x^2 -nx + 5 ) + (mx^2 + x -3 )

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coz what i was doing before was just subbing in 1 for x and solving that^^

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but u add them first? its kinda confusing coz

fluid shore
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Well, can you see that x^2 and mx^2 have a common factor of x^2?

trim fable
#

oh

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yes

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i do see that

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but when u add isn't it

fluid shore
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Yeap

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So $mx^2+x^2 = x^2(m+1)$

obsidian monolithBOT
trim fable
#

hmm

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why +1?

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uh

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oh..

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nvm

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u factored the x^2

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hmm ok makes sense

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waitttt

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😦

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why is it

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m-n=-1???

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im getting m-n

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@fluid shore 😦

fluid shore
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:///

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Uh wait can you post the question again?

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Sorry btw, i’m in camp so i’ll have to come and go as things get busy

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@trim fable

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Like, post the entire question

harsh cipher
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hi question

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question 6c. What does cos t stand for?

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theta?

clever inlet
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It's just a letter after all

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A variable

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I think it's safe to assume that's a function d in terms of t

harsh cipher
#

omg you're right haha

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amplitude 1/4 and vertical displacement -1

trim fable
#

oh ok

fluid shore
#

Okay so

trim fable
#

😛

fluid shore
#

$f(x) + g(x) = h(x) = (x^2-nx+5) + (mx^2 + x -3) = (m+1)x^2 + (1-n)x +2$

obsidian monolithBOT
fluid shore
#

^Do you understand what i've written above?

trim fable
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yeah

fluid shore
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Okay so

trim fable
#

wait

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why +2 ?

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OH

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OMG

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LOL

fluid shore
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5-3 is what?

trim fable
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thats what i did

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i wrote -2..

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wait but i still wont get

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m-n=-1

fluid shore
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$h(x) = (m+1)x^2 + (1-n)x + 2$

obsidian monolithBOT
fluid shore
#

No forget about what you've gotten before

trim fable
#

oh

fluid shore
#

What you have now is what matters

trim fable
#

alright

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YES

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OK

fluid shore
#

^Good life lesson tbh

trim fable
#

😛

#

YEAHH

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thanks for that inspirational life lesson

fluid shore
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So, you have been told that (1,3) and (-2,18) satisfy h(x)

trim fable
#

yes

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btw

fluid shore
#

What does it mean for those points to satisfy h(x)?

trim fable
#

questionn about that

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the y coordinate would be insignificant right

fluid shore
#

Nope, it is significant

trim fable
#

OOOOOOOOOOHHHHHHHHHHHHH

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OMGGGGGGGGGGGGGGGGGGG

fluid shore
#

What does it mean for those points to satisfy h(x)

trim fable
#

U MAKE THE EQUATION EQUAL TO ITTTTTTTTTTTTTT

fluid shore
#

Indeed

trim fable
#

wowwwwwwwwwww

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my brainnnnn

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wow thanks

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LOL

fluid shore
#

So h(1) = 3 and h(-2) = 18

trim fable
#

oh just to clarify coz i think i forgot

fluid shore
#

Then, you'll get two equations in two unknown variables m & n

trim fable
#

yeah

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ok ikwhat to do now 😄

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tho like question about it

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u know how i was adding before

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whats the difference between adding it the way u showed me or just

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subbing things right away and then solving

fluid shore
#

Well, you see

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(1,3) and (-2,18) satisfy f(x)+g(x), not f(x) and g(x) individually

trim fable
#

also for h(x) is i say h(1) then I sub in one right

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oh

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ye but if u were to do

fluid shore
#

Like, you don't know if they satisfy f(x) and g(x) individually. You can't say that f(1) = 3. You can say that f(1) + g(1) = 3

trim fable
#

OHH

fluid shore
#

Yeap, you substitute x = 1 into it

trim fable
#

ok

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so u always say that

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like for the next one

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18= f(-2) + g(-2)

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right

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so i should start off a question by stating something like that

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3= ( 1)^2 -n(1) + 5) + (m(1)^2 +1-3)
3= 1 -n +5 +m -2
3=-n+m+4
-1=n+m

fluid shore
#

Uh no

trim fable
#

oh so what i did before was right I was just not making it equal to y

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yeah ik i wanted to see

fluid shore
#

You should start off the question by finding h(x) explicitly

trim fable
#

if i got the answer thhat way

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and it worked out

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whys that?

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is that process considered wrong

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idk for me i feel like it really simplifies things a lot, i do get ur way buut its kinda complicated

fluid shore
#

Well, there is a common consensus that working in variables does allow you to generalize things easily

trim fable
#

yeah

fluid shore
#

That is, suppose I give you two other pairs of numbers that, supposedly, satisfy h(x) = f(x)+g(x)

trim fable
#

wow tho this questions pretty fun

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lol

fluid shore
#

If you didn't have h(x) written down explicitly, you'd have to do the entire calculation again

trim fable
#

oh

fluid shore
#

But if you did have it written down explicitly, it'd be way easier for you to get to the end

trim fable
#

what do u mean by explicitly

fluid shore
#

For this specific problem, it's not a big issue. For other problems, it can be an issue

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Like, a formula for h(x)

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Like the one that I showed you a while ago

trim fable
#

oh

fluid shore
#

Also, question's

trim fable
#

?

fluid shore
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Apostrophes are important

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🙂

trim fable
#

yeah

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LOL

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hey also

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determining the domain and range for

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composite functions confuse me a bit and

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like can we do this together

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so for fog u compare inner to outer right
so the range of g(x) and make that the domain of f(x)

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but like its really confusing 😦

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i do get it at times but then i just blank out

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like we use graphs to do it

fluid shore
#

I have two functions that are defined as follows:

$f:\bR \rightarrow \bR$ and $g: \bR \rightarrow \bR$

obsidian monolithBOT
trim fable
#

yeah

fluid shore
#

That's what your functions are

trim fable
#

what does that mean

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x is an element of the reals

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for both right

fluid shore
#

Yes

trim fable
#

ok

fluid shore
#

You can use any real number. The functions are defined for all reals

trim fable
#

ok so for fog

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see the pink line is the range of g(x) and I made it the domain of f(x)

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but why is the domain for the composite gonna be XER ?

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also how would u find the range

fluid shore
#

Uh have you done the necessary reading on range and domain?

trim fable
#

what do u mean

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for each ye so

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for the first one Second one
Domain: x is an element of the reals x is an element of the reals
Range: Y>=0, y is an element of the reals y is an element of the reals

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OH BTW YAY I GOT THE ANSWERR!! n=3, m=2 🙂

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thanks for that help lol

fluid shore
#

Well, all you need to do is to see that f(g(x)) = x^2-8

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So, that's defined for every real number x

trim fable
#

YEAHH

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but question about that 😛

fluid shore
#

So that would be your domain

trim fable
#

it wouldn't always work

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that way tho right?

fluid shore
#

Well, it would though? I mean, I haven't encountered cases where that doesn't really work out

trim fable
#

really????

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coz my teacher said it wouldn't

fluid shore
#

To determine what the domain is, you just need to determine when that function is defined and when it isn't

trim fable
#

oh

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and what do u mean by that

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like if its valid? the points

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thats what my teacher says

fluid shore
#

So, for example, y = 1/x is defined for all real numbers aside from when x = 0

trim fable
#

yeah

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true

fluid shore
#

So its domain is given by $\bR-{0}$

trim fable
#

what about for more

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complicated equations hmm

obsidian monolithBOT
trim fable
#

let me show u one from my notes and try to do it algebraically

fluid shore
#

Sure

trim fable
#

ok so

#

f(x) = 1/x and g(x) = 1/x^2-1

#

those functions

fluid shore
#

Uh $f(x) = \frac{1}{x}$ and $g(x) = \frac{1}{x^2-1}$

obsidian monolithBOT
trim fable
#

yeahh

#

those

fluid shore
#

Okay

#

Be mindful of your parantheses

trim fable
#

ok

fluid shore
#

Okay so f(x) is clearly undefined at x = 0. g(x) is undefined at x = 1 and x = -1

trim fable
#

yes

#

wow..

#

so u can just do that

#

😮

#

my teacher drew it out

#

ill try to draw it to show u?

#

or do u get what i mean

fluid shore
#

Your teacher is dumb

#

You can draw it out and you should

trim fable
#

would that be right

fluid shore
#

Indeed, that's correct

trim fable
#

ohh yay

#

so then i can use that dor the domain and range of

fluid shore
#

However, keep in mind that the domain of f(g(x)) does not include x = 1 and x = -1.

trim fable
#

fog right?

#

why not?

fluid shore
#

Because computing f(g(x)) at x = 1 or x = -1 involves computing g(1) and g(-1), both of which are clearly undefined

trim fable
#

😮

#

tho like

#

undefined is when its equal to zeroa right so

fluid shore
#

No

trim fable
#

(1)^2-1 = 0

#

1/0

fluid shore
#

Yea division by 0 is undefined

trim fable
#

oh wait

#

yes

#

wait so it doesn't

#

work algebraically for this?

fluid shore
#

Well, it does though

trim fable
#

oh

fluid shore
#

We did it without drawing any graphs

trim fable
#

hmm

#

what about for

#

gof

fluid shore
#

We determined the domain without using graphs. The domain is the set of real numbers that don't include 1 and -1

#

Wel, try it

#

I can't be doing everything for you, right?

trim fable
#

yeah

#

ik but this is really helping

#

oh and these qre questions from the notes tho

#

that our teacher did with us soooo

#

i already have the answers for that 😛

#

i just wanted to see if i could do it an easier way than graphs..

#

OHH

#

one more thing

#

@fluid shore So I have a question about these

#

Ok so like i get the dividing one coz the first one has a lot of asymptotes so it would be

#

log2x/sinx

#

and the third one has multiple zeros so it means it would be

#

sinx/log2x

#

then the 4th graph (second row first one) has horizontal asymptotes and zeros

#

so would it be multiplication so (log2x)*(sinx)

#

@fluid shore

#

sorry for the ping if it annoys u

#

also addition would be the same either way so
(log2x) + (sinx)
1+0 =1 so end behaviour is positive

Subtraction
(log2x)-(sinx)
1-0=1 end behaviour is positive

(sinx)-(log2x)
0-1 end behaviour is negative

#

so then the last graph would be (sinx)-(log2x) ?

fluid shore
#

I mean, I'm sort of not sitting down with a pen and paper

#

So i can't just verify what your answers are

#

I mean, just graph them out on desmos and see if you're correct lol

trim fable
#

ohhhhhhhhhhhhhhhhhhhhhhhhhhhh

#

true true

#

but my question LOL

#

was how to determine the last two

#

these ones

#

(log2x) + (sinx)
1+0 =1 so end behaviour is positive

Subtraction
(log2x)-(sinx)
1-0=1 end behaviour is positive

#

unless someone else can help since ur busy and thats fine 😛

#

thanks soo much thoooooo 😄

trim fable
#

anyone?

#

lol

trim fable
#

how would we do this

willow bear
#

what is the domain of $\sqrt{x+1} - 2\log(-(x+1))$?

obsidian monolithBOT
harsh cipher
#

question

#

at π why is y -1.25 ?

#

y = -1.25

willow bear
#

what?

harsh cipher
#

hi Ann

willow bear
#

i don't understand your question

harsh cipher
#

at pi why do we move down 1 square which is equal to 0.25

#

I think we have to move down 4 squares

willow bear
#

why

harsh cipher
#

cos pi = (-1,0)

willow bear
#

what do you mean move down four squares

#

your amplitude is 0.25 aka one square

harsh cipher
#

ah I feel embarassed

#

thanks!

trim fable
#

hi @willow bear

#

😛

#

how are u

willow bear
#

can we cut the pointless filler convo that i'm absolutely not up for sustaining right now and you tell me whether or not what i said made it clearer how to proceed on your problem

trim fable
#

why oof..

harsh cipher
#

Yea I got it

#

Thanks for your help.

trim fable
#

umm..

#

i think she was talking to me @harsh cipher

#

LOL

willow bear
#

yes i was

trim fable
#

oh sorry

#

umm

#

idk what the domain for that is..

willow bear
#

do you know how to find the domain of a function defined by a formula

trim fable
#

uh

#

make it equal to 0?

willow bear
#

sigh

#

no, not even close

trim fable
#

i guess no then

#

ik by graphing

willow bear
#

go look this shit up or something

trim fable
#

oh um

#

ok

#

also

#

i had a question about this

#

first one would be log2x / sinx right?

willow bear
#

there's nothing else it could be

trim fable
#

then third one would be sinx/log2x

#

and then the fourth would be (sinx)(log2x)

#

then the last one is sinx-log2x right?

#

but then idk how to determine the last two

#

but im left with sinx+log2x and log2x-sinx

#

so then how would i determine those

willow bear
#

gee i don't fucking know

trim fable
#

oh

#

u dont?

#

u didn't learn this stuff before?

willow bear
#

the fifth and sixth graphs look like mirror images of one another so maybe they are log - sin and sin - log

trim fable
#

oh i got it

#

middle top is

#

log2x+sin

#

tho is it coz the start of it goes up

#

see that part of it

#

and second is sinx-log2x

#

@willow bear

safe kettle
#

x(t) = 2cos^2t - 2sin^2t
y(t) = 4 - [cos(2t)]^2

how do i solve this

#

using tri identities

stuck lark
#

wdym solve

safe kettle
#

like put it in a rectangular equation

#

@stuck lark

native sequoia
#

double angle formula for cos

safe kettle
#

that gets me 4 - (cos^2t - sin^2t)^2 and idk what to do from there

native sequoia
#

look at what you have in brackets and then look at x(t)

safe kettle
#

er

#

OH

#

hm

#

but x(t) is multiplied by 2 thougfh

#

the cos2t

#

ohh

#

i think i can see

#

x(t)/2 = cos^2t - sin^2t

#

then i can plug in for x(t)/2

#

k thx

native sequoia
#

np

safe kettle
#

i feel dumb now lol

#

aha

#

its a parabola

#

except @native sequoia how do you know where it's restricted

#

the domain and range

#

and t also

native sequoia
#

I'd say assume t is over the reals, and we know x(t)=2cos(2t), so...

safe kettle
#

errrr what?

native sequoia
#

what values does x(t) go over?

safe kettle
#

idk

#

infinite?

native sequoia
#

nah, think about the range of cos

safe kettle
#

why is it graphed sideways on desmos?

#

im confused

#

i thought cos was horizontal

#

remember when math used to be easy....

native sequoia
#

can you screenshot what you see on desmos

trim fable
#

yes tho it prob still is easy

#

im just getting dumber?

safe kettle
native sequoia
#

looks like desmos is letting the vertical axis be the t-axis for some godforsaken reason

safe kettle
#

oh

#

it's because of the x probably

#

wait so shouldn't x be infinite

#

goddamn alg 2 & below was so much easier

native sequoia
#

for t over the reals, 2cos(2t) has range -2 to 2

#

i.e. x(t) goes over the values between -2 to 2

safe kettle
#

huh

#

what

#

i thought the domain is infinite for sin and cos

#

and range is limited to whatever

#

or are we talking about the unit circle

#

i think i should just get some sleep

clever inlet
#

You are right

#

But

#

x(t) and y(t) are your outputs

safe kettle
#

eh whatever i'll figure it out in class tmrw

#

it's getting late

#

well at least comp sci is easy lmao

zealous sail
#

How can I solve

obsidian monolithBOT
zealous sail
#

symbolab says to use Newton Raphson, which has not been taught in my class, so I don't think we use that

#

and WA doesn't show any actual steps

trim fable
#

hi

#

question

#

how would u do

#

#3

clever inlet
#

What have you tried?

viscid thistle
#

f o g(x) = f(g(x))

#

For 1, we’d have: f(g(x))= x^2 - 8

#

Are there any restrictions on the domain?

#

No. We can input any real number

#

Now, for the range, we’re looking for values of x which output.

#

Looking at the function, we notice that x^2 is positive for all x

#

So, the minimum output of x^2 is 0.

#

Thus, the range, at the smallest, is -8.

#

And all numbers greater than -8 can be given.

#

So the range is all numbers >= -8

willow bear
#

So the range is all numbers >= -8
are you insistent on avoiding interval notation or sth

#

what stopped you from saying [-8, +∞)

viscid thistle
#

Didn’t think he’d understand that

stark trench
#

On my test there was this question... "There are 2 letters that dis include x and y, then 3 numbers from 0-9, the first of which cannot be be 0, and then any two letters but they can not be repeated."

#

So I did

#

24×24×9×10×10×26×25

#

Not sure if that is right

#

<@&286206848099549185>

#

Also not sure if I should use this ^

viscid thistle
#

Ping helpers after 15minutes, not before.

stark trench
#

Why?

#

That a rule or smthing?

viscid thistle
#

Yes

stark trench
#

Hmmm... interesting.

patent beacon
#

What?

viscid thistle
#

@patent beacon I’m wondering the same thing

tiny verge
#

what does 'dis' include mean?

viscid thistle
#

The way the question is worded is fucked

#

Disincluded = not included, I guess

patent beacon
#

Like is the answer a number?

viscid thistle
#

Yeah idk I assume so

#

His answer is def wrong tho [with this wording]

tiny verge
#

oh, exclude right

#

I'm guessing they're looking for letter letter number number number letter letter ?

#

perms for that

viscid thistle
#

Oh

patent beacon
#

So questions pretty much have to include "What is..."

willow bear
#

disinclude thonk

viscid thistle
#

That makes sense i think

patent beacon
#

Where's your "what is..."?

tiny verge
#

I would guess number of perms for a 7 blank long code with the given rules

#

Are you here @stark trench ?

stark trench
#

@tiny verge yep

#

Also the question is based off my memory

#

Not the exact thing

#

But the numbers are the same

#

Also I meant disinclude

#

But autocorrect gives it a space...

#

Essentially, it wanted us to use fundamental counting theory

#

With 7 spots

patent beacon
#

Are you asking "how many ways to make this string"?

stark trench
#

The first 2 were any letters that disincluded X and Y

tiny verge
#

hm, so 7 spots with allowing repeated numbers, not allowing repeated letters on the last 2 spots, and allowing repeated letters on the 1st two spots where you can't have x and y, yes?

stark trench
#

It was just a permutation problem with fundamental counting

#

Here is the thing...

viscid thistle
#

Exclude

#

Not disinclude

stark trench
#

At the end it says

patent beacon
#

I think you've got it right, then

stark trench
#

"The last 2 spots can be used for any letter, but these letters cannot be repeated"

#

I'm not sure if that refers to all previous letters

#

Or just from that point

#

So I was like...

tiny verge
#

hm, my thought exactly

stark trench
#

Do I use 22x21

#

Or 26x25

#

Idk tho

#

Anyways, fuck that test.

#

I looked back at my answers in my head.

#

And I got like 7-8 mc /26

#

Rip

winged cloak
willow bear
#

what's confusing you about this

winged cloak
#

I don't understand the calculation where does it come from

willow bear
#

it's not a calculation

winged cloak
#

So how do you get it?

willow bear
#

...you don't

#

well i mean

#

ok

#

you CAN sort of do some pseudo-algebraic manipulation here

#

like you can start from $\frac{f(x+h) - f(x)}{h} \approx f'(x)$

obsidian monolithBOT
willow bear
#

multiply through by h and add f(x) to both sides and you'll get what your paper says

winged cloak
#

Oh OK I understand I read it like
f '(x+h) ~ f(x) + f '(x) h

willow bear
#

so you inserted an extra apostrophe in there is what you're saying

winged cloak
#

Yeah I thought it was the derivate

#

But why do you that

#

It s a simplification

willow bear
#

...sometimes this form can be useful?

winged cloak
#

With the basic formula you try to reach f(x+h)?

#

Thats the question

#

I think I get it now thanks for the help

sterile halo
#

coefficient of x^4 in the expansion (2x+1)(x-3)^6. how do you solve this again?

vapid elk
#

How to solve x=5arctan(x)?

patent beacon
#

Cannot

wide niche
#

I mean, you can, but it's not exactly straightforward precalc

patent beacon
#

Cannot algebraically

#

You can approximate solutions with many methods, up to you if you're for that

wide niche
#

I got something like this:

x = 5*arctan(x)
x/5 = arctan(x)
x = tan(x/5)     => what values of x make this true?
patent beacon
#

x = 0 is a solution

#

But that's the only one that can be expressed exactly

wide niche
#

keeping in mind of course that tan(x)=sin(x)/cos(x)

#

@patent beacon tangent is periodic though

#

hrm... the 5 throws a wrench into it

#

I see your point

vapid elk
#

Ok. thanks @patent beacon

hallow flicker
#

if i have this function with like 2 turning points but only one point cross the x axis how do i figure out the function

severe prawn
#

what does turning point mean

#

critical point

#

or inflection point

#

?

hallow flicker
#

like it stops sloping up wards then goes downwards

#

wait let me show you

severe prawn
#

so a critical point

#

okay so

hallow flicker
#

sure

severe prawn
#

are you given the form of the function?

#

like is it a polynomial?

hallow flicker
#

yea

severe prawn
#

what is

#

it

hallow flicker
#

what

#

the function isnt given

#

it is a polynomial

#

here are the points where it crosses

#

the turning point

severe prawn
#

of what degree

#

are you given?

hallow flicker
#

you are given like a point

severe prawn
#

can you show

hallow flicker
#

the stuff in the picture is all your given

hallow flicker
#

yea

severe prawn
#

i dont think thats the problem

#

but okay

#

can you show the problem

#

you are given?

#

from the textbook or whatever

hallow flicker
#

find the function of the graph

#

its not from a textbook

severe prawn
#

okay

#

what degree do you think

#

this polynomial is of

hallow flicker
#

idk what a degree is

severe prawn
#

highest power

hallow flicker
#

but im assuming its you mean the power

#

3

severe prawn
#

okay

#

so the function is of the form

#

ax^3+bx^2+cx+d

#

right?

hallow flicker
#

yea

severe prawn
#

for real a b c d

#

okay

#

now f(x) = ax^3+bx^2+cx+d

hallow flicker
#

yea

severe prawn
#

for real constants abcd

#

we can first find this constant d

#

f(0) = d

#

whats f(0)

hallow flicker
#

ok

severe prawn
#

from the graph

hallow flicker
#

that 27

severe prawn
#

okay

#

so now for this graph

#

the function is ax^3+bx^2+cx+27

hallow flicker
#

ok

severe prawn
#

can you keep going?

#

keep plugging in points

#

and doing system of equations?

#

and also by knowing that at turning points

#

f' is 0?

hallow flicker
#

no

severe prawn
#

no what

#

you cant?

hallow flicker
#

ok so the turning poitns are labels

#

labeled

#

right

severe prawn
#

okay

#

f(x) = ax^3+bx^2+cx+27

#

f'(x) = 3ax^2+2bx+c

#

f'(3.523) = 0

#

f'(-0.189) = 0

#

f(2.097) = 0

hallow flicker
#

ok

severe prawn
#

those are your 3 equations

#

for your 3 constants ig

#

can you solve them?

#

do you know how i got those equations

hallow flicker
#

i know how you got 2

severe prawn
#

what 2

hallow flicker
#

but the one with the 2. 097 wouln't be zero

#

cuz its not like a turning point, the top two are

severe prawn
#

its ar oot

#

its ar oot

#

i wrote f(2.097) = 0

#

not f'

hallow flicker
#

oh ok

#

my bad

severe prawn
#

yea

#

its okay np

#

got it now?

hallow flicker
#

yea so what else do i do

#

no

severe prawn
#

write out the equations

#

and solve for your constants

#

unfold your definition

#

you know f(x)

hallow flicker
#

i can try

severe prawn
#

ax^3+bx^2+cx+27

#

sure

hallow flicker
#

ok i cant do it

severe prawn
#

what did yo utry

hallow flicker
#

oh wait

#

i think i got it

#

i assum i set them all qual to each other then solve for a b and c right?

severe prawn
#

you can do that ig

#

f'(3.523)=f'(-0.189)=f(2.097)=0

#

its just a system of equations

hallow flicker
#

ok i got it

#

ill ask you if i cant end up solving it

severe prawn
#

sure

hallow flicker
#

ok i cant do it

#

but look 2 of the equestions have the same value

prisma prairie
#

is b^x = 1/b^-x?

hallow flicker
#

yes

runic cradle
#

I can't seem to figure out part A of this problem. Can anyone help? (please ping me if you do so I can make sure I see it)

#

I got an answer (about 38.838 mi) very close to the real answer (about 38.65 mi) by assuming that KROK was broadcasting at a 50 degree angle to the east as well but I don't know if I could assume that or, if I could, why that makes sense.

hallow flicker
#

yea ok ill explain how to get the angle

#

i assum from there you can do the work

#

There is another angle so now you should be able to calculate all the angles

#

@runic cradle

runic cradle
#

ohhh that makes sense now

#

thank you

lethal oracle
#

(y-2)^2=4(x+3)

#

Why is the focus of this parabola (-2,2)

#

I thought the focus is (h+p,k)

#

And p is equal to 1

trim fable
#

@fluid shore

#

im really having trouble 😦

languid crane
#

With what

fluid shore
#

What’s up

#

Sorry was busy with stuff

harsh cipher
#

question

#

at pi/2 or 2pi/4 why is the y-coordinate 0.75?

#

equation given for the above answer was y= cos(x- pi/4)

#

I just couldn't get that point when trying to graph

willow bear
#

it's not supposed to be 0.75, the graph is honestly a bit poor

#

it looks like they approximated the sinusoid by stitching together pieces of a parabola

harsh cipher
#

well its 0.707 or something to be exact...

willow bear
#

no

#

it's 1/sqrt(2)

#

anyway yeah this isn't a good graph. i can see the seams. it's not clean at all.

harsh cipher
#

okay. why the y coord is at where it is when x = 0?

willow bear
#

same reason. it's supposed to be 1/sqrt(2) too.