Question

F(x) = ax + b
Jika f(-2) = -13 dan f(3) = 12 maka nilai f(5) ?

Answer 1

F(x) = ax + b
f(-2) = -2a + b = -13
f(3)  = 3a + b = 12  _
         -5a = -25
           a = 5

3a + b = 12
3.5 + b = 12
15 + b = 12
b = -3

f(5) = ax + b = 5.5 + (-3) = 25 - 3 = 22

Answer 2

F(x) = ax + b
F(-2) = a(-2) + b
-13 = -2a + b ---> pers 1
,
F(3) = a(3) + b
12 = 3a + b ---> pers 2
,
Eliminasi pers 1 dan 2
-2a + b = -13
3a + b = 12
----------------- -
-5a = -25
a = -25/-5
a = 5
,
3a + b = 12
3(5) + b = 12
b = 12 - 15
b = -3
,
maka:
f(5) = ax + b
= 5(5) + (-3)
= 25 - 3
= 22