Question

How do you sovle this system of equations: `3x - y = 12;- 3x + y = 15`?

Answer 1

See the entire solution process below:

Explanation:

Step 1) Solve the second equation for `y` while keeping the equation balanced:

`-3x + y = 15`

`-3x + 3x + y = 15 + 3x`

`0 + y = 15 + 3x`

`y = 15 + 3x`

Step 2) Substitute `15 + 3x` for `y` in the first equation and solve for `x` while keeping the equation balanced:

`3x - (15 + 3x) = 12`

`3x - 15 - 3x = 12`

`0 - 15 = 12`

`-15 = 12`

Because we know `-15 != 12` there is no solution for this system of equations. In fact both of these equations are parallel with a slope of `m = 3`