Question

Explain the answere of marked mcq's?how these option are correct?

Answer 1

I do not get those answers. Please see below.

Explanation:

`26)`

I don't understand the notation `d/dx = tan3x`

But `d/dx(tan3x) = sec^2 3x * d/dx(3x) = 3sec^2 3x`, which is closest to (A), but (A) still has the wrong argument.

I also do not understand the notation `sec^+ 3x`

`29)`

`f(g(x)) = sinx` and `g(x) = sqrtx`

Differentiating with respect to `x`, we get (using the chain rule)

`f'(g(x)) * g'(x) = cosx` and `g'(x) = 1/(2sqrtx)`

So `f'(g(x)) = 2sqrtx cosx` and

`f'(g(pi)) = f'(sqrtpi) = 2sqrtpi cospi = -2sqrtpi`

Which is choice (C).