diketahui f(×)=ax+b. jika f(-1)= -8 dan f(2)= 13, nilai f(5)=

f(-1) = a(-1)+b = -8
.......= -a+b = -8
f(2) = a(2)+b = 13
.......= 2a+b = 13

-a+b = -8
2a+b = 13
-------------- --
-3a = -21
....a = 7
-
-7+b = -8
......b = -1

f(x) = 7x+(-1) = 7x- 1
f(5) = 7(5)- = 35-1 = 34

Diketahui
f(x)  = ax+b
f(-1) = -1a + b = -8
f(2)  = 2a + b = 13

*Eliminasi b

-1a + b =  -8
 2a + b = 13
---------------- (-)
-3a      = -21
   a      = -21 : -3
           = 7

*Substitusikan a ke salah satu persamaan
2a + b = 13
2(7) + b = 13
b = 13 - 14
b = -1

maka, a = 7 dan b = (-1)

f(5) = 5a + b
       = 5(7) + (-1)
       = 34

Mohon maaf jika ada kesalahan