Question

Given ƒ(x) = −3x + 21, find x when ƒ(x) = 6. A) −2 B) 3 C) 5 D) 7

Answer 1

x = 5

Explanation:

We have,

`f(x) = -3x + 21` .....(1)

It is required to find x when the value of f(x) = 6

Put f(x) = 6 in equation (1) such that we get :

`6 = -3x + 21\\\\3x=21-6\\\\3x=15\\\\x=5`

The value of x is 5 if f(x) = 6.