Answer:
x = -3
y = -5
(-3, -5)
Step-by-step explanation:
We can solve this system of equations by elimination. This is when you either add OR subtract the equations (depending on the situation) to <u>eliminate one variable</u>, allowing you to solve for the other. To do this, we need one variable with the same coefficient in BOTH equations.
9x - 4y = -7 X3=> 27x - 12y = -21 (New equation is still equivalent)
7x - 12y = 39
Both equations have negative "12y" in them. If you subtract - 12y from - 12y, you get 0, eliminating the variable. <u>Subtract the two equations.</u>
. 27x - 12y = -21 Subtract each term in the equation.
<u>- 7x - 12y = 39</u> Keep equal signs aligned
. 20x - 0 = -60 'y' eliminated. -12y - (-12y) = 0
. 20x = -60 Isolate 'x'
. 20x/20 = -60/20 Divide both sides by 20
. x = -3 Solved for 'x'
<u>Substitute 'x' for -3</u> in any equation.
9x - 4y = -7
9(-3) - 4y = -7 Substitute. Simplify multiplication.
-27 - 4y = -7 Isolate 'y' now
-27 + 27 - 4y = -7 + 27 Add 27 on both sides
-4y = 20 Left side cancelled out 27, right side simplified by adding.
-4y/-4 = 20/-4 Divide both sides by -4
y = -5 Solved for 'y'
Therefore the solution is when 'x' is -3 (x = -3) and when 'y' = -5 (y = -5).
You can also write the solution as an ordered pair, like coordinates, which are written (x, y). The solution would be (-3, -5).
