suatu fungsi linear f(x) = ax + b, apabila f(2) = 1 dan f(1) =-2 maka nilai f(-2) adalah

f(x) = ax + b
f(2) = 2a + b = 1
f(1) = a + b = - 2
------------------------(-)
a = 3
a + b = - 2
3 + b = - 2
b = - 2 - 3 = - 5
f(x) = 3x - 5
f(-2) = 3(-2) - 5 = (-11)

f(x) = ax + b
f(2) = 2a + b = 1 < - persamaan 1
f(1) = a+b = -2 < - persamaan 2
Persamaan 1 - persamaan 2
a=3
b =-5

f(x) = 3x - 5
Jadi, f(-2) = 3(-2)-5 = -11