nomor 5 gimana ya. ???

Kelas 8 Matematika
Bab Fungsi

f(x) = ax + b

f(1) = a + b = -2
f(-2) = -2a + b = 1

-2a + b = 1
a + b = -2
----------------- -
-3a = 3
a = -1

a + b = -2
-1 + b = -2
b = -2 + 1
b = -1

f(x) = -x - 1

f(x) = 1,5
-x - 1 = 1,5
-x = 1,5 + 1
x = -2,5