Question

Bab komposisi fungsi
diket: g(x)= 12/mx+n , g(1)= -4 , g(3)= -12 .
Jika g(x)= x, maka nilai x yg memenuhi adalah..
A. 3 dan 4
B. 2 dan -6
C. -3 dan 4
D. 1 dan 5
E. -2 dan 6

Answer 1

G(x) = 12/ (mx + n)
g(1) = 12/ (m + n)
-4 = 12 / (m + n)
-4m - 4n = 12
m + n = -3

g(3) = 12/ (3m + n)
-12 = 12 / (3m + n)
-12 (3m + n) = 12
3m + n = -1
m + n = -3 -
2m = 2
m = 1
m + n = -3
1 + n = -3
n = -4

g(x) = 12 / (x -4)
x = 12 / (x - 4)
x² - 4x = 12
x² - 4x - 12 = 0
(x - 6)(x +2) = 0
x = 6  atau x = -2
Jawaban E