Question

Diketahui f(x) = ax + b. jika f(-2) = 1 dan f(1) = -2, nilai 2a - b =
a. 2
b. 1
c. -1
d. -2

Answer 1

F(x) = ax + b
f(-2) = 1 dan f(1) = -2
2a - b = ?

>>f(-2) = a × -2 + b
    1 = -2a + b

>>f(1) = a × 1 + b
    -2 = a + b

Eliminasi:
1  = -2a + b
-2 = a + b
__________-
3 = -3a
a = 3/-3 = -1

-2 = a + b
-2 = -1 + b
-2 + 1 = b
b = -1

2a - b = 2 × -1  - (-1) = -2 + 1 = -1