Question

How do you solve the system of equations `x+ 2y = 3` and `- 2x + y = 1`?

Answer 1

Pick either one of the equations and make either `x` or `y` the subjects of the formula and substitute the value of either `y` or `x` into the other equation.

Explanation:

I.e. `" "x=3-2y" "` (from first equation)

Now substitute `x` above into second equation:

`-2(3-2y)+y=1`

`-6+4y+y=1`

`-6+5y=1`

`5y=7`

Therefore

`y=7/5`

Now substitute the `y`-value into the equation to find `x`:

`-2x+7/5=1`

`-2x=5/5(=1) -7/5`

`x=1/5`

Thus, `x` and `y` for the 2nd equation `=1/5` and `=7/5`.

You must again substitute either into the 1st equation to find those values. Just remember to check the answers!