Diketahui suatu fungsi

titik(1,2)
2=a+b ...(1)
titik(4,3)
3=4a+b ...(2)

•eliminasi (1) dan (2)

a+b=2
4a+b=3
______ _
-3a=-1
a=1/3

1/3 + b= 2
b= 5/2

maka, 3(a²-b)=3((1/3)²-(5/2))=3((1/9)-(5/2))=3(2/18 - 45/18) = 3(-43/18)=-129/18=-43/9