Question

How do you solve the system of equations `x + y = - 3` and `x + 2y + 8= 0`?

Answer 1

We would use elimination method to solve the system as I shall outline below.

The solutions are `x = 2` and `y = -5`

Explanation:

`x + y = -3` be equation `(1)`
`x + 2y = -8` be equation `(2)`

Subtracting equation `(2)` from `(1)`,
`x+y - (x +2y) = -3 - (-8)`
`implies -y = 5`
`implies y = -5`

Now substituting this value of `y` in one of the equations (in this case `(1)`),

`x - 5 = -3`
`implies x = 2`