Question

What is the solution of the system? Use elimination.
3x - 4y = 9
-3x + 2y = 9

Answer 1

[-9, -9]

Explanation:

Here is how the Eliminasyon Metòd is done:

{3x - 4y = 9

{-3x + 2y = 9

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-2y = 18; -9 = y [plug this back into both equations for y to get -9 = x]

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Answer 2

You add two equations together to eliminate a variable. This particular problem is nice, because it's already setup to eliminate X.

3x - 4y = 9
-3x + 2y = 9

When we add these two together, 3x - 3x cancels each other out, leaving us with 0x, or nothing.

We continue with -4y + 2y (leaves us with -2y) and 9+9 (18).

-2y = 18

18/-2 = -9.

Now we have y = -9, and we can go back into the problems to solve for x.

3x - 4(-9) = 9

3x + 36 = 9.

3x = -27

x = -9.

Confirm with the final equation:

-3(-9) + 2(-9) = 9
27 - 18 = 9
9 = 9 --- Confirmed.