Porisma

A hint to get started

Reverse an arctangent chain and use a principal sine substitution

(i) Find ∫etan⁡−12x1+4x2 dx\displaystyle\int\dfrac{e^{\tan^{-1}2x}}{1+4x^2}\,dx. marks

(ii) Given that −π2<θ<π2-\dfrac\pi2<\theta<\dfrac\pi2, use the substitution x=sin⁡θx=\sin\theta to find ∫x21−x2 dx\displaystyle\int\dfrac{x^2}{\sqrt{1-x^2}}\,dx. marks

[2018/MI/Promo/PU2/I/9]

CJC · Review Problems · Question 10

Use the stated angle interval to select the positive cosine branch before cancelling.

Read the worked solution