suatu fungsi dirumuskan F(X )= ax + b jika F(2 )= 14 dan F(3) =- 1 , nilai f( 7) adalah

f(2) = 2a + b = 14
f(3) = 3a + b = -1
------------------------ --
-a = 15
a = -15

2a + b = 14
2x(-15) + b = 14
b = 14+30 = 44

f(x) = -15x + 44