fungsi f ( X) = px + q mempunyai f(-1) = 2 dan f (1)=8. nilai p - 2q adalah ....

f(-1) = -1p + q = 2
f(1) = p+q = 8

pake eliminasi

-2p = - 6
p = 3

jika p = 3 maka q =

3 + q = 8
q = 5


p -2q = 3 - 2 × 5 = -7