Question

How do solve the following linear system?: `3x – 2y = 7 , 11x + 3y + 7 = 0`?

Answer 1

`3x-2y=7..........(i)`
`11x+3y+7=0 implies 11x+3y=-7............(ii)`
Multiply `(i)` by `3` and (ii) by 2 and add
`implies9x-6y=21`
`22x+6y=-14`

By addition we have
`31x+0=7`

`implies x=7/31`

Put `x=7/31` in `(i)`

`implies 3(7/31)-2y=7`

`implies 21/31-2y=7`

`implies 2y=21/31-7`

`implies 2y=(21-217)/31`

`implies 2y=-196/31`

`implies y=-98/31`