Question

Find f(-7) if f(x) = 2х+ 8.

Answer 1

use the substitution method

f(x)= 2x+8

f(-7)= 2(-7)+8

Mutiply first then add

Positive number times negative number = negative number

= -14+8

f(-7)= -6

Answer : f(-7)= -6

Answer 2

f(-7) = -6

Explanation:

Put x = -7 to f(x) = 2x + 8:

f(-7) = 2(-7) + 8 = -14 + 8 = -6