Question

If f(x + 2) = 2x + 3 then find f-'(4).​

Answer 1

Given:

The function is

`f(x+2)=2x+3`

To find:

The value f'(4).

Solution:

We have,

`f(x+2)=2x+3`

Putting
`x+2=t` and
`x=t-2` we get

`f(t)=2(t-2)+3`

`f(t)=2t-4+3`

`f(t)=2t-1`

Differentiate with respect to t.

`f'(t)=2(1)-0`

`f'(t)=2`

At
`t=4`, we get

`f'(4)=2`

Therefore, the value of f'(4) is 2.