Tolong jelasin yaa, kakak-kakak yang baik! hehe

f(x)=ax–b, f(2)=11, f(–1)=2, f(3)=....???
f(2)=11
a(2)–b=11
2a–b=11 ........(1),
f(–1)=2
a(–1)–b=2
–a–b=2 .........(2)
eliminasi pers(1) dan (2)
2a–b=11
–a–b=2
..................–
3a=9
a=3
substitusikan a=3 ke pers(1)
2(3)–b=11
6–b=11
–b=5
b=–5
jadi,f(x)=ax–b
f(3)=3(3)–(–5)
=9+5
=14
jawabannya D.
semoga membantu ya...