Question

Rumus f(x) Ax + b

Jika f(3)=15 dan f(5)= 20
Tentukan
A:nilai a dan b
B:bentuk fungsi
C:f(-2)

Answer 1

A) f(x) = Ax + B
f(3) = 15
f(3) = 3a + b = 15
f(5) = 5a + b = 20

dieleminasi (dikurang)
f(5)-f(3)
2a = 5
a = 5/2

substitusi
f(3) = 3a + b = 15
f(3) = 3 (5/2) + b = 15
f(3) = 15/2 + b = 15 (kali 2 semua)
15+2b = 30
2b = 15
b = 15/2

b)
f(x) Ax + b
f(x) = 5/2 x + 15/2

c) f(-2) = 5/2 kali -2 + 15/2
f(-2) = -5+15/2 (jadikan per 2 semua)
f(-2 ) = -10/2 + 15/2
f(-2) = 5/2