diketahui fungsi f(x) = ax + b. jika f(3) = 1 dan f(-2) = -9. nilai f(-5) adalah

f(x) = ax + b
f(3) = 3a + b = 1
f(-2) = -2a + b = -9

3a + b = 1
-2a + b = -9
baris pertama dikurangkan dg baris kedua, diperoleh
5a = 10
a = 10/5
a = 2

3a + b = 1
3(2) + b = 1
6 + b = 1
b = 1 - 6
b = -5

f(x) = 2x - 5
f(-5) = 2(-5) - 5 = -10-5 = -15