Diketahui f(x) = ax+b. Jika f(2) = 8 dan f(1)=2, maka nilai a dan b adalah....

f(x) = ax+b
f(1) = a(1)+b
a+b = 2 ... (1)
f(2) = a(2)+b
2a+b = 8 ... (2)

eliminasi pers. 1 dan 2
2a+b = 8
a+b = 2
________ -
a = 6

subtitusi ke pers. 1
a = 6
a+b = 2
6+b=2
b = 2-6
b = -4