Question

How do you solve the system of equations `3x + 7y = - 3` and `x + \frac { 7} { 4} y = - \frac { 2} { 3}`?

Answer 1

`x=1/3`
`y=-4/7`

Explanation:

`3x+7y=-3`

`x+7/4y=2/(-3)`
Multiply everything by `-3`:
`-3(x+7/4y)=-3(2/(-3))`
`-3x-21/4y=2`

Add the 2 equations (elimination):
`3x+7y=-3`
`-3x-5.25y=2`

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`1.75y=-1`
`y=1/(-7/4)`
`y=-4/7`

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Substitute `y=-4/7` into one of the original equations:
`x+7/4(-4/7)=-2/3`
`x-1=-2/3`
`x=1/3`