tolongin ngitung 2 soal itu dong... pleasee

15. f(x)=ax+b
f(1)=a.1+b=3
f(-3)=a.(-3)+b=11
____________=
f(1)=a+b=3
f(-3)=-3a+b=11
___________-
4a=-8
a=-2

a+b=3
-2+b=3
b=3-2
b=1 (C)

15) f( x ) = ax + b
f(1) = a + b = 3
f(-3) = - 3a + b = 11
---------------------------(-)
4a = - 8
a = - 2
subtitusi ke pers :
a + b = 3
- 2 + b = 3
b = 3 + 2
b = 5
jadi
a = - 2
b = 5
( D )

16) f ( x ) = px + q
f(1) = p + q = - 5
f(-2) = - 2p + q = - 11
-----------------------------(-)
3p = 6
p = 2
subtitusi ke pers :
p + q = - 5
2 + q = - 5
q = - 5 - 2
q = - 7
f(x)= px + q
f(x) = 2p - 7
f(t) = 2t - 7 = 85
2t = 85 + 7
2t = 92
t = 46 ( B )