Question

A function is given.
f(x) = 4x – 8
What is the input of the function when the output is 20?
I

Answer 1

Given:

The function is

$f(x)=4x-8$

To find:

The input of the function when the output is 20.

Solution:

We have,

$f(x)=4x-8$

Here, x is input and f(x) is output.

Put f(x)=20 in the given function to find the input of the function when the output is 20.

$20=4x-8$

$20+8=4x$

$28=4x$

Divide both sides by 4.

$\dfrac{28}{4}=x$

$7=x$

Therefore, the required input value is 7.