Suatu fungsi ditentukan dengan rumus f(x) = ax + b. Jika f(3)=12 dan f(-5) = -28, tentukan nilai f(12)

jawab

f(x) = ax+ b
f(3)  = 12
f(-5) = -28

f(3) -f(-5) = 12 - (-28)
(3- (-5)) a = 12+28
8a = 40
a = 5

f(3)= 12
b = 12 - 3a
b = 12- 3(5)
b = 12-15
b = - 3

f(x) = ax +  b
f(x) = 5x -3 

f(12) = 5(12) - 3
f(12)= 60 - 3
f(12) = 57