diketahui fungsi f(x) = ax-b, dengan f(2)=11 dan f(-1)=2. Nilai f(3) adalah? a. 4 b. 8 c. 12 d. 14 tolong jawab beserta caranya.

Memakai cara substitusi


f(x) = ax - b
11 = 2a - b
2 = -a - b
_________ -
9 = 3a
a = 3

-3 -b = 2
-b = 5
b = -5

f(3) = 3(3) + 5
      = 14 (D)

ini pakai cara eliminasi
f (2) = a.x - b = 11
= a. 2 - b = 11
f (-1) = a.x - b = 2
= a.(-1) - b =2

eliminasi = a.2 - b = 11
= a. (-1) - b = 2
lalu dikurang (-b) - (-b) itu habis
= a3 =9
= a = 9/3
= a = 3

lalu mencari b kita bisa pakai yg mana saja
f (2) = a.x - b =11
= 3.2 -b =11
= 6-b =11
=b = 11-6
= b = 5

lalu
f (3) = a.x -b
= 3.3 - 5
= 9 - 5
= 4
jawabannya 4