Question

Given f(x) = 3x^2 + 2x – 1 and g(x) = 4x-5 find ( g of f) (-2)

Answer 1

`\text{Given that,}\\\\f(x) = 3x^2 +2x -1\\\\f(-2)=3(-2)^2 +2(-2) -1 = 12-4-1=7\\\\g(x) = 4x -5\\\\\text{Now,}\\\\(g \circ f) (-2)\\\\=g(f(-2))\\\\=g(7)\\\\=4(7)-5\\\\=28-5\\\\=23`

Answer 2

23

Explanation:

Evaluate f(- 2) then substitute the value obtained into g(x)

f(- 2) = 3(- 2)² + 2(- 2) - 1 = 3(4) - 4 - 1 = 12 - 5 = 7 , then

g(7) = 4(7) - 5 = 28 - 5 = 23