Question

Solve the system of equations {3x-y=6 { 6x+y=21 explain the steps on how to do this please

Answer 1

I would set the equations on top of each other and subtract

6x+y=21
- 3x-y=6
________
3x=15

Then solve for x
X=5

To solve for y, plug 5 in for x for one of the equations

Answer 2

The easiest way to solve this is by elimination.

3x - y = 6
6x + y = 21

Since you have a negative and positive y with the same coefficients (1), they cancel, and you add the other terms so it would look like:

9x = 27

Then solving for x leaves you with x = 3

Then you take the x value of three and plug it into to either of the equations, so

3(3) - y = 6

9 - y = 6

subtracting 9

-y = -3

then dividing by -1

y = 3

so the solution is x = 3 y = 3 or (3,3)