Question

How do solve the following linear system?: `-9x+5y=1 , -3x+7y=-1`?

Answer 1

`x=y=-1/4`

Explanation:

`(-9x+5y)-3*(-3x+7y)=1-3*(-1)`

`-9x+5y+9x-21y=1+3`

`-16y=4`, so `y=4/(-16)=-1/4`

Hence,

`-9x+5*(-1/4)=1`

`-9x-5/4=1`

`-9x=9/4`, thus `y=(9/4)/(-9)=-1/4`