Answer: (3,-6)
x = 3 & y = -6
Explanation:
y = -2x
y = 5x - 21
FINDING X
Since y = -2x we can substitute the y in the second equation with -2x.
-2x = 5x - 21
There is two x’s so you have to get rid of one, in this case 5x, by subtracting it from both sides.
-2x = 5x - 21
-5x -5x
—————
-7x = -21
Then we are going to isolate the x by dividing -7 by both sides.
-7x = -21
—— —— - 7 divided by 7 is 1 so it
-7 -7 would be 1x or x
x = 3
So our x is 3. Now we move on to finding y.
FINDING Y
To do that, we are going to use the first equation.
y = -2x
We are going to plug in the x.
y = -2(3)
y = -6
So our y is -6.
CHECKING
If you want to check it to make sure you have the correct answer you can just plug all of it in to the equation.
y = 5x - 21
-6 = 5(3) - 21
-6 = 15 - 21
-6 = -6