Question

Suatu fungsi ditentukan dengan rumus f(x) = ax + b. Jika f(-2) = 17 dan f(5) = -32, f(12) = ....
A. -81
B. -53
C. 28
D. 67

Answer 1

F(x) = ax + b
f(-2) = -2a + b
17 = -2a + b

f(5) = 5a + b
-32 = 5a + b

-2a + b = 17
5a + b = -32
_________ -
-7a = 49
a = -7

-2a + b = 17
-2(-7) + b = 17
14 + b = 17
b = 3

f(x) = -7x + 3
f(12) = -7(12) + 3
= -84 + 3
= -81

Answer 2

F(5) -> 5a + b = -32
f(-2) -> -2a + b = 17
---------------- -
7a = -49
a = -7
5a + b = -32
5(-7)+b = -32
-35 + b = -32
b = -32 +35
b = 3

f(12) -> 12(-7) + 3
-84 + 3
-81