which of the following is equal to

Question

Let f(x) = 4- 3x    which of the following is equal to f’ (-1)

 

a) -7               b) 7            c) -3              d) 3                e) cannot be determined 

 

Where do i start ? 

Answer 1

f(x) = 4 - 3x

f(-1) = 4 - 3(-1)

f(-1) = 4 + 3

f(-1) = 7

 

b)

Answer 2

First, we need to take the derivative of f(x) because it is asking for the value of the derivative when x=-1.

 

 

f'(x) = -3

 

The derivative is a constant value.  This means for any value of x, the value of the derivative is always -3.

 

 

Answer is (c).