# ∫ Sin − 1 ( 3 X − 4 X 3 ) D X - Mathematics

Sum
$\int \sin^{- 1} \left( 3x - 4 x^3 \right) \text{ dx }$

#### Solution

$\int$  sin–1 (3x – 4x3)dx
Let x = sin θ
⇒ dx = cos​ θ.dθ
θ = sin–1 x

$\int$  sin–1 (3x – 4x3)dx =
$\int$  sin–1 (3 sin ​θ – 4 sin3 ​θ) . cos ​θ d​θ
= ∫ sin–1 (sin 3​θ) . cos ​θ d​θ

$= 3\int \theta_I . \cos _{II} \theta d\theta$

$= 3\left[ \theta\int\cos \theta d\theta - \int\left\{ \frac{d}{d\theta}\left( \theta \right) - \int\cos \theta d\theta \right\}d\theta \right]$

$= 3\left[ \theta . \sin \theta - \int1 . \sin \theta d\theta \right]$

$= 3\left[ \theta . \sin \theta + \cos \theta \right] + C$

$= 3\left[ \theta . \sin \theta + \sqrt{1 - \sin^2 \theta} \right] + C$

$= 3\left[ \left( \sin^{- 1} x \right) . x + \sqrt{1 - x^2} \right] + C \left( \because \theta = \sin^{- 1} x \right)$

Concept: Indefinite Integral Problems
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#### APPEARS IN

RD Sharma Class 12 Maths
Chapter 19 Indefinite Integrals
Exercise 19.25 | Q 35 | Page 134