Suatu fungsi dirumuskan f(x) = ax + b. jika f(-2) = 14 dan f(3) = -1, nilai f(7) adalah... A. -13 B. 13 C. 16 D. 19 JAWAB DENGAN MENGGUNAKAN CARA

f(x) = ax + b
f(-2) = a.-2 + b
14 = -2a + b ••• (1)
f(3) = a.3 + b
-1 = 3a + b ••• (2)

-2a + b = 14
3a + b = -1
---------------- -
-5a = 15
a = -3

3a + b = -1
3 (-3) + b = -1
-9 + b = -1
b = 8

Maka,
f(7) = -3.7 + 8
•••• = -21 + 8
•••• = -13
Jawaban : A