Question

How do you solve the following system?: `4x +9y =-4 , -21x +2y = 4`

Answer 1

`x=-44/197`
`y=-68/197`

Explanation:

`4x+9y=-4` --- (1)
`-21x+2y=4` --- (2)

From (1),
`4x+9y=-4`
`4x=-4-9y`
`x=1/4(-4-9y)` --- (3)

Sub (3) into (2)

`-21(1/4(-4-9y))+2y=4`
`-21/4(-4-9y)+2y=4`
`21+189/4y+2y=4`
`197/4y=-17`
`y=-17times4/197`
`y=-68/197` --- (4)

Sub (4) into (3)
`x=1/4(-4-(9times-68/197))`
`x=-44/197`