Question

How do you solve 11x + 3y + 7 = 0 , 2x +5y - 21 = 0?

Answer 1

I found:
`x=-2`
`y=5`

Explanation:

You can try by multiplying the first equation by `-2` and the second by `11` and then add together (in columns) the two equations to get:

`{((color(red)(-2))xx11x+3y+7=0),((color(red)(11))xx2x+5y-21=0):}`

`{(-22x-6y-14=0),(22x+55y-231=0):}` add them:

`0+49y-245=0`
`y=245/49=5`

substitute this value into the first equation:
`11x+15+7=0`
`11x=-22`
`x=-22/11=-2`