1.diketahui SPLDV:ax-by=-2 dan 2bx+ay=20. himpunan penyelesaian SPLDV tersebut {(2,4)} .nilai 2a-b=...... 2.sistem persamaan linear ax-3y=138 dan 5x +by =240 me

1) kalau tdk salh : HP = {(x,y)} = {(2,4)}
*ax-by=-2
a(2)-b(4)=-2
2a-4b=-2
*2bx+ay=20
4b+4a=20
*2a-4b=-2
4a+4b=20
_________+
6a = 18
a=3
*2bx+ay=20
4b+3(4)=20
4b = 8
b=2
*2a-b= 2(3)-2 = 4

2) diket : HP = {(24,-30)}
*ax-3y=138
24a+90=138
24a = 48
a = 2
*5x+by=240
120-30b=240
-30b=120
b= -3
ditannya : a+2b
a+2b = 2+2(-3) = -4