Suatu fungsi dinyatakan dengan rumus f(x) =ax +b.jika f (-2)=-8 dan f(5) =13 maka f (7) adalah

Kelas 8 Matematika
Bab Fungsi

f(-2) = -2a + b = -8
f (5) = 5a + b = 13
........---------------------- -
-7a = -21
a = -21/-7
a = 3

5a + b = 13
5 . 3 + b = 13
b = 13 - 15
b = -2

f (x) = 3a - 2

f (7) = 3 . 7 - 2
f (7) = 21 - 2
f (7) = 19