19. Fungsi f dinyatakan dengan rumus f(x) = ax + b. Jika f(2) = 3 dan f(–3) = 13, makanilaidari –a + b adalaH

f(2) = 2a + b
3 = 2x + b

f(-3) = -3a + b
13 = -3a + b

eliminasi :

2x + b = 3
-3a + b = 13. -

5a = -10
a = -2

maka nilai b : 2(-2) + b = 3
-4 + b = 3
b = 7
= -a + b
= -(-2) + 7
= 9