diketahui : f(x)=p×+q jika f(1) = -8 dan f(3) = 12 tentukan f(-3)

f(×) = px + q
f(1) = -8
p(1)+q = -8
p+q = -8 .....(a)

f(x) = px + q
f(3) = 12
p(3)+q = 12
3p + q = 12 ..... (b)

dieliminasi (a) - (b)
{p+q = -8} - {3p+q = 12}
-2p = -20, p = 10. q= -18

f(-3) = px + q
= 10(-3) + -18
= -48