Question

How do you solve the following system using substitution?: `y=x-5, y=2x`

Answer 1

`x=-5`
`y=-10`

Explanation:

You simply have to substitute `x` or `y` from the first equation to `x` or `y` in the second equation.

So in the first equation, the value of `y` is `x-5`. You just have to substitute this value into `y` in the second equation.

`[1]color(white)(XX)y=2x`

`[2]color(white)(XX)x-5=2x`

`[3]color(white)(XX)-5=2x-x`

`[4]color(white)(XX)color(blue)(x=-5)`

Now that we have the value of `x`, we can plug it into either of the two equations to solve for `y`.

`[1]color(white)(XX)y=x-5`

`[2]color(white)(XX)y=(-5)-5`

`[3]color(white)(XX)color(red)(y=-10)`