rumus f(x)=ax+b f(-3)=-7 f(5)=17. tentukan nilai f(3a-2)

f(x) = ax + b
f(-3) = -3a+b => -3a+b = -7 (i)
f(5) = 5a+b => 5a+b = 17 (ii)

eliminasi (i) dan (ii)
-3a+b = -7
5a+b = 17
_________-
-8a = -24
a = 3

subtitusi nilai a ke (i)
-3(3) + b = -7
b = 2

maka nilai dari
f(3a-2) = f(3(3)-2) = f(7)
f(7) = (3)(7)+2 = 21 + 2 = 23