Question

Solve. Question
1) 2X+Y=5; 3X-Y=5.
2) 2Y-X=0; 10X+15Y=105.
3) 2X-7Y=7; 3X+Y=22

Answer 1

1 )2x+y=5
+ 3x-y=5
x=2
taking value x=2 in equation 1
2x+y=5
2×2+y=5
4+y=5
y=1

2)Multiplying equation 1 by 10
10x-20y =0
+ -10x+15y=105
x=21
substituting x=21 in 1
2x-y=0
2×21-y=0
41-y=0
y=41





3)Multiplying equation 2)by 7
21x+7y=154
+2x-7x=154
x=7
substituting x=7 in equation 2
3x+y=22
3 ×7+y=22
21+y=22
y=1