Q. Evaluate the integral and express your answer in simplest form.∫36−16x22dxAnswer:
Recognize inverse trigonometric function: Recognize the integral as a form of the inverse trigonometric function. The integral resembles the form of the inverse sine function, which has the integral formula ∫a2−u21du=arcsin(au)+C, where a is a constant. In this case, we can try to match the integral to this form by factoring out constants from the square root.
Factor out constant from square root: Factor out the constant from the square root to match the inverse sine integral form.∫36−16x22dx=∫42(9−x2)2dxNow, factor out the 42 from under the square root to get:∫49−x22dx=∫29−x21dx
Substitute u to transform integral: Substitute u=3x to transform the integral into the standard form.Let u=3x, then du=31dx, and dx=3du.Substitute x=3u into the integral:∫29−(3u)21⋅3du=∫29−9u23duSimplify the integral:∫29(1−u2)3du=∫61−u23du= ∫21−u21du
Integrate using inverse sine function: Integrate using the inverse sine function.The integral is now in the standard form for the inverse sine function:∫21−u21du=21arcsin(u)+C
Substitute back original variable: Substitute back the original variable x into the integral.Since u=3x, we substitute back to get the final answer:21arcsin(3x) + C
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