Question

How do solve the following linear system?: `5x-y=3 , x+y=-4`?

Answer 1

`x = -1/6," "y = -3 5/6`

Explanation:

An alternative method is to write each equation with y as the subject. Both equations allow this to be done easily.

`y = 5x-3 " and "y = -x-4`

And now by equating the `y`'s, we get
`y = y`

`:.5x-3 =-x-4`

`6x = -1 rArr " "x = -1/6`

There are now two equations to calculate a value for `y`,which is quite nifty, because we can then check that each equation gives the same value for `y`.

`y = 5(-1/6) -3 = -3 5/6`
`y = -(-1/6)-4 = -3 5/6`