Question

Solve by Cross multiplication method x+2y+1=0 and 2x-3y-12=0

Answer 1

x = 3

y = -2

Explanation:

x + 2y + 1 = 0

2x - 3y - 12 = 0

Multiply first equation by -2.

-2x + -4y + -2 = 0

2x - 3y - 12 = 0

Add equations.

0x + -7y - 14 = 0

Solve for y.

-7y = 14

y =-2

Put y as -2 in the first equation and solve for x.

x+2(-2)+1=0

x + -4 + 1 = 0

x = 0 + 4 - 1

x = 3

Answer 2

`\boxed{x = 3, y = -2}`

Explanation:

`x+2y +1 = 0`

=>
`x+2y = -1` -------------------(1)

`2x-3y-12 = 0`

=>
`2x-3y = 12` -------------------(2)

Multiplying (1) by 2

=>
`2(x+2y) = 2(-1)`

=>
`2x+4y = -2` ------------------(3)

Subtracting (3) from (2)

=>
`2x-3y+2x-4y = 12+2`

=> -3y-4y = 14

=> -7y = 14

Dividing both sides by -7

=> y = -2

Now, Put y = -2 in Eq (1)

=> x+2(-2)+1 = 0

=> x -4+1 = 0

=> x - 3= 0

Adding 1 to both sides

=> x = 3