Jawab:

1. (gof)(-2) = 8

2. f(x) = 2x - 4

Penjelasan dengan langkah-langkah:

1. f(x) = 2x - 3 dan g(x)= x² + 2x - 3

(gof) (x) = g (f(x))

            = g (2x - 3)

            = (2x - 3)² + 2(2x - 3) - 3

            = 4x² - 12x + 9 + 4x - 6 - 3

            =  4x² - 8x

            = x² - 2x

(gof) (-2) = x² - 2x

              = (-2)² - 2(-2)

              = 4 + 4

              = 8

2. g(x) = 2x + 5 dan (fog)(x) = 4x + 6

2x + 5 = a

2x = a - 5

x = a - 5 / 2

fog(x) = 4x + 6

f(a) = 4(a - 5 / 2) + 6

     = (4a - 20 / 2) + 6

     = 2a - 10 + 6

     = 2a - 4

f(x) = 2x - 4