jika diketahui f(2)=5 dan f(5)=8 dengan rumus fungsi f(x)=ax+b, nilai f(10) adalah

f(x) = ax + b
f(2) = 5
a.2 + b = 5
2a + b = 5 ...(1)

f(5) = 8
a.5 + b = 8
5a + b = 8 ...(2)

eleminasi
2a + b =5
5a + b = 8
dikurang =
-3a = -3
a = 1

substitusi
2a + b = 5
2.1 + b = 5
2 + b = 5
b = 5-2 = 3

f(10) = ax + b
= 1.10 + 3
= 10 + 3 = 13