Fungsi f(x) = a.x + b.x. Jika f(-1) = 2 dan f(1) = 8, maka nilai dari f(4) adalah…..

F(x) = a.x + b.x
f(-1) = 2 — -1a -1b = 2
f(1) = 8 —- 1a -1b = 8. +
—————
-2b = 10
b= -5

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

f(4) = 3.4 + -5.4
= 12 + (-20) = -8