Diketahui suatu fungsi di rumuskan oleh f(x) = ax + b.jika f(2) = -1 dan f(5) = 8 tentukan nilai dari f(10)

f(x) = ax + b
Eliminasi dahulu :)
f(2) = 2a + b = -1
f(5) = 5a + b = 8
_____________ -
= -3a + 0 = -9
= a = -9/-3
= a = 3

Substitusi ke 5a + b = 8
5(3) + b = 8
15 + b = 8
b = 8-15
b = -7

f(10)= 10(3) + (-7)
f(10)= 30 - 7
f(10) = 23

Kelas 8 Matematika
Bab 2 - Fungsi

f(x) = ax + b
f(2) = 2a + b = -1 ......(i)
f(5) = 5a + b = 8 ......(ii)

Eliminasi nilai b
2a + b = -1
5a + b = 8
________ _
-3a = -9
a = -9/-3
a = 3

Substitusikan nilai a
2a + b = -1
2(3) + b = -1
6 + b = -1
b = -1 - 6
b = -7

Rumus fungsi
f(x) = ax + b
f(x) = 3x - 7

Nilai f(10)
f(10) = 3(10) - 7
f(10) = 30 - 7
f(10) = 23