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Have you tried that?

Ohhh just a sec! Im gonna give that a try :)

So is it 81 - (x - 9)^2 ?

|dw:1438583101045:dw|

Correct

Ah yes! Great! :)

|dw:1438583282353:dw|

I think my 3rd step is wrong, isn't it?

yea theres something wrong with the power

I knew it xD lol How would I simplify it?

|dw:1438584976279:dw|

Right!

I mean is my step from (-u^2 + 81)^(1/2) to (-u+9) correct?

i remember you have to divide by 18+1

\[\int\limits_{}^{}(ax+b)dx=\frac{ 1 }{ a }\times \frac{ (ax+b)^{a+1} }{ a+1 }\]\[a \neq-1\]

\[\int\limits_{}^{}(ax+b)^ndx\]oh god the lag with the equation is horrible

Lol xD I'm kinda lost

the x^2 is the messy thing

I don't exactly know what to do with it xD but it totally looks wrong

where did ya power go?

you need to add 1 to 1/2 and divide it by 1+1/2

I considered it as (-u^2)^(1/2) and 81^(1/2) which is completely wrong, haha

thought*

Oh, maybe a double substition could work?

Dang it.

This is not a pleasant integral lol
Your next substitution is \[u = 9\sin(t)\]

@Astrophysics i tried that with a calculator and the answer looks a little crazy

@Astrophysics how'd you get 9sin(t) ? :O

astro's trig integral

Hmmm... @Jhannybean I'm trying to figure out what you did there lol

Its called a double substitution.

But don't use it, it's not going to be pretty.

i got it.

\[\sqrt{81-u^2}du \longrightarrow \sqrt{a-x^2}dx ~\therefore~ x=a\sin(t)\]

@Astrophysics I tried putting in wolfram's answer before, but it said it was incorrect >.<

It's a trig substitution rule that you learn in calculus.

you wan symbolab's answer?

https://www.symbolab.com/solver/step-by-step/%5Cint%5Csqrt%7B18x-x%5E%7B2%7D%7Ddx/?origin=suggestion

Oooh nice

always good to have more options

Yeah try that answer, it uses the exact approach I was talking about

Alrighty... thats a lot to type in xD haha hold up xD

I mean maybe there is a simpler way, I don't know.

i don't know how i forgot much of my integration stuff right after the test

I don't know am I typing it in incorrectly or what? XD

You put it in wrong, it's all over 2

Ohhh shoooot! >.<

Still wrong...

Your doing the wrong integral

it looks like you have enter your answer on a different question

bahaha!

XDDDDD

Oh my goodness ahahaha

dont blame me its almost 1 am

pretty cool you can enter the answer over and over again

hehehehe
My bad :P

yay!

much wow, such correct

xD

I know! Lol but i still don't understand how they get that >.<

Go over the symbolab result I guess

it shows all the steps

thats why i chose em over wolfram

here is the trick though...http://www.sosmath.com/calculus/integration/trigsub/trigsub.html

Yeah, i guess i should! It sucks that wolfram doesn't show all the steps unless you go Pro XD

Yeah :(

Nice work everyone! Collective work is always good, especially for bad integrals!

and @Zale101 :P

I was going all nuts over this one lol