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anonymous
 one year ago
I don't know how to approach this one... Help would be very much appreciated!!
anonymous
 one year ago
I don't know how to approach this one... Help would be very much appreciated!!

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Zale101
 one year ago
Best ResponseYou've already chosen the best response.218xx^2 is a standard quadratic equation. If you converted (18xx^2) into the vertex form, you can easily apply usub.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Ohhh just a sec! Im gonna give that a try :)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0So is it 81  (x  9)^2 ?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Ohh I see! So then it turns into \[\int\limits \sqrt{u^2 +81} du = \int\limits (u^2+81)^{1/2}du = \int\limits (u+9)du = \frac{ 1 }{ 2 }u^2 + 9u\] Is that right?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I think my 3rd step is wrong, isn't it?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0yea theres something wrong with the power

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I knew it xD lol How would I simplify it?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0dw:1438584976279:dw

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I mean is my step from (u^2 + 81)^(1/2) to (u+9) correct?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0i remember you have to divide by 18+1

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0\[\int\limits_{}^{}(ax+b)dx=\frac{ 1 }{ a }\times \frac{ (ax+b)^{a+1} }{ a+1 }\]\[a \neq1\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0\[\int\limits_{}^{}(ax+b)^ndx\]oh god the lag with the equation is horrible

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Lol xD I'm kinda lost

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0the x^2 is the messy thing

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I don't exactly know what to do with it xD but it totally looks wrong

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0where did ya power go?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0you need to add 1 to 1/2 and divide it by 1+1/2

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I considered it as (u^2)^(1/2) and 81^(1/2) which is completely wrong, haha

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@saseal but then what about inside the brackets?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I can? But isn't that just like breaking up a root like this... \[\sqrt{a+b} = \sqrt{a} + \sqrt {b} \] And I though that was incorrect.. Is it not?

Astrophysics
 one year ago
Best ResponseYou've already chosen the best response.2\[\int\limits \sqrt{u^2+81}du \implies \int\limits \sqrt{81u^2}du \] do another substitution, requires trig.

Jhannybean
 one year ago
Best ResponseYou've already chosen the best response.0Oh, maybe a double substition could work?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0yea i feel i should have gone \[\int\limits_{}^{}\sqrt{18xx^2}dx = \int\limits_{}^{}(18xx^2)^{\frac{ 1 }{ 2 }}dx\]\[u=x^2\]\[du=2x\]

Astrophysics
 one year ago
Best ResponseYou've already chosen the best response.2This is not a pleasant integral lol Your next substitution is \[u = 9\sin(t)\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Haha! Right!! Something to do with these... ? \[\sin^2x+\cos^2x =1\] and \[\tan^2x +1 = \sec^2x \] Or am I on the wrong track again xD lol

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@Astrophysics i tried that with a calculator and the answer looks a little crazy

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@Astrophysics how'd you get 9sin(t) ? :O

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@saseal which one did you try?

Jhannybean
 one year ago
Best ResponseYou've already chosen the best response.0\[\int \sqrt{u^2+81}du \rightarrow \int (u^2+81)^{1/2}du \rightarrow \\ v=u^2+81 ~,~ dv=\frac{2}{3}u^3du\rightarrow \frac{3dv}{2} \\ \sf \text{ it gets messy with algebraic subs :(...}\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0astro's trig integral

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Hmmm... @Jhannybean I'm trying to figure out what you did there lol

Jhannybean
 one year ago
Best ResponseYou've already chosen the best response.0Its called a double substitution.

Jhannybean
 one year ago
Best ResponseYou've already chosen the best response.0But don't use it, it's not going to be pretty.

Jhannybean
 one year ago
Best ResponseYou've already chosen the best response.0\[\sqrt{81u^2}du \longrightarrow \sqrt{ax^2}dx ~\therefore~ x=a\sin(t)\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@Astrophysics I tried putting in wolfram's answer before, but it said it was incorrect >.<

Jhannybean
 one year ago
Best ResponseYou've already chosen the best response.0It's a trig substitution rule that you learn in calculus.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0you wan symbolab's answer?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0https://www.symbolab.com/solver/stepbystep/%5Cint%5Csqrt%7B18xx%5E%7B2%7D%7Ddx/?origin=suggestion

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0always good to have more options

Astrophysics
 one year ago
Best ResponseYou've already chosen the best response.2Yeah try that answer, it uses the exact approach I was talking about

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Alrighty... thats a lot to type in xD haha hold up xD

Astrophysics
 one year ago
Best ResponseYou've already chosen the best response.2I mean maybe there is a simpler way, I don't know.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0i don't know how i forgot much of my integration stuff right after the test

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I don't know am I typing it in incorrectly or what? XD

Astrophysics
 one year ago
Best ResponseYou've already chosen the best response.2You put it in wrong, it's all over 2

Astrophysics
 one year ago
Best ResponseYou've already chosen the best response.2Your doing the wrong integral

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0it looks like you have enter your answer on a different question

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Oh my goodness ahahaha

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0dont blame me its almost 1 am

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0pretty cool you can enter the answer over and over again

Astrophysics
 one year ago
Best ResponseYou've already chosen the best response.2Lol I always hated answering questions on the computer...that's why I like assignments where you can hand it in, and yay!

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0much wow, such correct

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I know! Lol but i still don't understand how they get that >.<

Astrophysics
 one year ago
Best ResponseYou've already chosen the best response.2Go over the symbolab result I guess

Astrophysics
 one year ago
Best ResponseYou've already chosen the best response.2it shows all the steps

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0thats why i chose em over wolfram

Astrophysics
 one year ago
Best ResponseYou've already chosen the best response.2here is the trick though... http://www.sosmath.com/calculus/integration/trigsub/trigsub.html

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Yeah, i guess i should! It sucks that wolfram doesn't show all the steps unless you go Pro XD

Astrophysics
 one year ago
Best ResponseYou've already chosen the best response.2Nice work everyone! Collective work is always good, especially for bad integrals!

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Yeah! Thanks all!! @Jhannybean @saseal @Astrophysics :D

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I was going all nuts over this one lol

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Oh yes!! And thanks to @Zale101 as well! :D Thanks for reminding me! Haha
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