Jawabanmu

2014-06-18T11:19:50+07:00
A = b
berarti i = i ; j = j ; k = k
p+q = -5 => p = -q-5
3p+7q = 21
-10 = -10

subtitusi
3(-q-5) + 7q=21
-3q -15 + 7q = 21
4 q = 36
q = 9

3p + 7q = 21
3p + 63 = 21
3p = -42
p = -14

:)
2014-06-18T11:21:50+07:00
 \left \{ {{p+q=-5}|×3 \atop {3p+7q=21}} \right.

-  \left \{ {{3p+3q=-15} \atop {3p+7q=21}} \right.

       -4q = -36
          q =  \frac{-36}{-4}
          q = 9
p+q=-5
p+9=-5
p=-5-9
p=-14

nb. adanya nilai p&q.