Diketahui g(x) = x – 1 dan (f o g)(x) = 4×2 – x. jika f(a) = 5, maka tentukan nilai a!

Jawaban:

a = -2

a = 1/4

Penjelasan:

g(x) = x – 1

(fog)(x) = f(g(x)) = 4x^2 – x

misal:

x – 1 = y

x = y + 1

f(y) = 4(y + 1)^2 – (y + 1)

f(y) = 4(y^2 + 2y + 1) – y – 1

f(y) = 4y^2 + 8y + 4 – y – 1

f(x) = 4x^2 + 7x + 3

f(a) = 5

4a^2 + 7a + 3 = 5

4a^2 + 7a – 2 = 0

(a + 2)(4a – 1) = 0

a = -2

a = 1/4

maaf klw salah jadikan jawaban terbaik