Diketahui f(x) = ax+b. Jika f(-3) = 7 Dan f(2) = -3, nilai f(5) adalah

f(x) = ax + b
f(-3) = 7 ----> f(-3) = -3a + b = 7
f(2) = -3 ----> f(2) = 2a + b = -3

-3a + b = 7
2a + b = -3
---------------- (-)
-5a = 10
a = 10/-5
a = -2

-3(-2) + b = 7
6 + b = 7
b = 7-6
b = 1

maka nilai f(5) = 5(-2) + 1 = -10 + 1 = -9 (d)

f(x) = ax + b

f(-3) = ax + b
7 = a(-3) + b
7 = -3a + b..... Pers. (1)

f(2) = ax + b
-3 = a(2) + b
-3 = 2a + b... Pers. (2)

✔Persamaan 1 dan 2 eliminasi

-3a + b = 7
2a + b = -3
..................... –
-5a = 10
a = -2

✔tentukan nilai b

2a + b = -3
2(-2) + b = -3
-4 + b = -3
b = -3 + 4
b = 1


Sehingga persamaan f(x) adalah
f(x) = ax + b
f(x) = -2x + 1

Maka, f(5)
= -2(5) + 1
= -10 + 1
= -9

Jawaban D