My friend gave me a nasty integral: #int sqrt{1 + (-sin(0.7x^{1.18})0.826x^{0.18})} dx#. Can anybody give me some advice on how to solve this?

#int sqrt{1 + (-sin(0.7x^{1.18})0.826x^{0.18})} dx#

I'm having a bit of trouble with this one. I've tried fitting this into the form #int sqrt{a^2 + x^2} dx#.

However, it's a bit tricky considering the fact that there is an inner trigonometric function that has to be dealt with. I tried substitution leaving me with something with the form #int(sqrt{a^2 + x^2}/cos(f(x)))dx# (where f is some function of x) and then I tried integration by parts but I got lost since I had to mix integrals with #du# and #dx# and it all became very messy.

Any advice?

1 Answer
Apr 10, 2018

Please see below.

Explanation:

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This is a difficult integral that will result in an incomplete #Gamma# Function. You can use Wolframalpha.com to obtain the result. Two different forms of the answer are shown below:

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For #gamma > 0#

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For #0 < gamma < 1# and #x^1.18 > 0#

enter image source here