Diketahui g(x) =px+q. Jika g(-3)=21 dan g(4)=7.maka nilai p + q adalah

g(x) = px + q
g(-3) = p(-3) + q = 21
= -3p + q =21 ....1)
g(4) = p(4) + q = 7
= 4p + q = 7 ....2)

metode eliminasi persamaan 1 dan 2
-3p + q = 21
4p + q = 7
----------------- -
-7p = 14
p = 14/-7 = -2

subtitusi p = -2 ke persamaan 2
4p + q = 7
4(-2) + q = 7
-8 + q = 7
q = 7 + 8 = 15

jadi, p + q = -2 + 15 = 13