Suatu fungsi dirumuskan f(x) =ax+b. Jika f(-2) = 14 dan f(3) =-1, nilai f(7) adalah

f(x)= ax+b
f(-2)= -2a+b= 14
f(3)= 3a+b= -1
Eliminasi
(3a+b)-(-2a+b)= -1-14
5a= -15
a= -3
Substitusi ke salah satu persamaan
3a+b= -1
3(-3)+b= -1
b= -1+9= 8

f(x)= -3x+8
f(7)= -3.7+8= -21+8= -13

maaf foto ini salah


f(-2)= 14
=a(-2)+b= 14
= -2a+b= 14

f(3)= -1
=a(3)+b= -1
= 3a+b= -1

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


2a+b= 14
2(3)+b= 14
6+b= 14
b= 14-6
b= 8


nilai f(7)= -3(7)+8
= -21+8
= -13