Question

How do you find the solution of the system of equations `3x - y = 9` and `2x + y = 6`?

Answer 1

We can add the two equations to eliminate `y`

Adding the 2 equations will give us:

`(3x - y) +(2x + y) = 9 + 6`

`3x - cancel(y) +2x + cancel(y) = 15`

`5x= 15`
`color(blue)(x = 3)`

Substituting this value of `x` in the first equation we get `y` :

we are given:
`3x - y = 9`

`3*3- y = 9`
`9 - y= 9`
`0 = y`

`color(blue)(y=0)`

The solution to these system of equations is:

`color(green)(x = 3 , y = 0`