Question

Diketahui sistem persamaan 3×-2y=27 dan 5×+3y= 26. nilai dari ×-2y adalah...
A. -13
B. -1
C. 1
D. 13

Answer 1

3x-2y=27 x5
5x+3y=26 x3

15x-10y=135
15x+9y=78
______________-
-19y=57
y=-3

3x-2x=3x+6=27
3x=21;x=7
x-2y=7-(-6)=7+6=13
D.13

Answer 2

3x - 2y = 27         x3 = 9x - 6y = 81
5x + 3y = 26        x2 = 10x + 6y = 52
                                  ------------------------------  +

19x = 133
   x = 133 : 13
  x = 7

3x-2y=27
3(7)-2y=27
21-2y=27
-2y=27-21
-2y=6
y=6:-2
y=-3

x-2y = ???
7 - 2(-3) = ???
7 - (-6) = ??
7 + 6 = 13
 (D)