Question 1090371: Solve the system of equations by the method of elimination.
8x + 8y = 0
-16x - 12y = 20
Don't understand how dividing by -2 and then adding gets an answer.
Answer by addingup(3677)   (Show Source):
You can put this solution on YOUR website! If you don't like dividing, we can multiply:
8x + 8y = 0 multiply all sides times 2:
16x + 16y = 0 (0 times any number = 0, so this doesn't change)
Now, to that number add the next number, like this:
16x + 16y = 0
+
-16x - 12y = 20
---------------------
0x + 4y = 20
4y = 20
y = 5
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
now let's do it dividing by 2 (not by minus 2, but by 2):
Take -16x - 12y = 20 and divide all sides by 2, so you end up with -8x - 6y = 10, then add to the other number:
8x + 8y = 0
+
-8x - 6y = 10
-------------
0x + 2y = 10
2y = 10
y = 5
Happy learning,
John
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