Differentiate the function f(x) = 2x^3 + (cos(x))^2 + e^x

When differentiating a function that is the sum of three different parts we can differentiate each part separately:

a) 2x3 is easy to differentiate. We remember the rule d/dx[axb] = abxb-1. So

2x3 --> 6x2

b) (cos(x))2 is a bit harder. We can use the chain rule, as we have a function raised to a power. The chain rule is:

d/dx[(g(x))n] = n(g(x))n-1 * d/dx[g(x)]

Also we need to remember that cos(x) differentiates to -sin(x)

So we have that

(cos(x))2 --> -2cos(x)sin(x).

c) ex is the easiest of the lot: it doesnt change when differentiated. 

ex --> ex

Therefore the final answer is:

d/dx[f(x)] = 6x2 - 2cos(x)sin(x) + ex

SP
Answered by Seth P. Maths tutor

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