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Mathematics 14 Online
OpenStudy (thatonegirl_):

please help!! Integral using inverses

OpenStudy (thatonegirl_):

\[\int\limits_{0}^{\sqrt{3}} \frac{ dx }{ \sqrt{4-x^2} }\]

OpenStudy (misty1212):

HI!!

OpenStudy (thatonegirl_):

Hello :D

OpenStudy (misty1212):

looks pretty much like an arcsine right?

OpenStudy (thatonegirl_):

yup!

OpenStudy (misty1212):

in fact, if it was \[\int \frac{dx}{\sqrt{1-x^2}}\] it would be arcsine

OpenStudy (thatonegirl_):

mhm i'm having trouble trying to factor out the 4 :S

OpenStudy (misty1212):

\[4-x^2=4(1-\frac{1}{4}x^2)=4(1-(\frac{x}{2})^2\]

OpenStudy (thatonegirl_):

so would there be a sqrt over the 4?

satellite73 (satellite73):

yeah, that was just the algebra under the radical

OpenStudy (mathmale):

Misty's presentation needs one more right parenthesis: \[4-x^2=4(1-\frac{1}{4}x^2)=4(1-(\frac{x}{2})^2)\]

OpenStudy (thatonegirl_):

ah okay

OpenStudy (thatonegirl_):

so then u would just be x/2 ?

OpenStudy (misty1212):

the four will come out of the radical as a two

OpenStudy (misty1212):

yup, you can do a u - sub and change the limits of integration while you are at it

OpenStudy (thatonegirl_):

ah okay i got it! That's mainly what was confusing me xD Thank you!!

OpenStudy (thatonegirl_):

I got pi/3 btw which i just put in and was right :)

OpenStudy (misty1212):

\[\color\magenta\heartsuit\]

OpenStudy (misty1212):

yay

OpenStudy (thatonegirl_):

Thank you!

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