Diketahui f(x^2 + x + 2) = x2– x - 2 dengan x ≥ 0 maka nilai f(4) = …. (A) -2 (B) -1 (C) 3 (D) 8 (E) 16

Question

Matematika Diposting : 2017-12-30 Diupdate : 2021-02-01 ulyakamilia

Pertanyaan

Diketahui f(x^2 + x + 2) = x2– x - 2 dengan x ≥ 0 maka nilai f(4) = ….
(A) -2 (B) -1 (C) 3 (D) 8 (E) 16

Answer 1

f(x² + x + 2) = x² - x - 2

f(4) = ...
x² + x + 2 = 4
x² + x - 2 = 0
(x + 2)(x - 1) = 0
x = -2 ; x = 1

x ≥ 0 ---> x = 1

f(4) = 1² - 1 - 2
f(4) = -2