Differentiation Question 234

Question: $ \frac{d}{dx}( x^{3}{{\tan }^{2}}\frac{x}{2} ) $ =

[AISSE 1979]

Options:

A) $ x^{3}\tan \frac{x}{2}.{{\sec }^{2}}\frac{x}{2}+3x{{\tan }^{2}}\frac{x}{2} $

B) $ x^{3}\tan \frac{x}{2}.{{\sec }^{2}}\frac{x}{2}+3x^{2}{{\tan }^{2}}\frac{x}{2} $

C) $ x^{3}{{\tan }^{2}}\frac{x}{2}.{{\sec }^{2}}\frac{x}{2}+3x^{2}{{\tan }^{2}}\frac{x}{2} $

D) None of these

Show Answer

Answer:

Correct Answer: B

Solution:

$ \frac{d}{dx}( x^{3}{{\tan }^{2}}\frac{x}{2} )=3x^{2}{{\tan }^{2}}\frac{x}{2}+2x^{3}\tan \frac{x}{2}{{\sec }^{2}}\frac{x}{2}.\frac{1}{2} $

$ =x^{3}\tan \frac{x}{2}{{\sec }^{2}}\frac{x}{2}+3x^{2}{{\tan }^{2}}\frac{x}{2} $ .