Question

What's the solution to the following system of equations?

−3x−9y=18
4x+3y=12
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x=( , )
y=( , )


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Answer 1

x = 6 and y = -4 or (6,-4)

Explanation:

To solve the system, multiply an equation to create same coefficients for one variable. Then stack the equations and perform elimination to solve for each variable.

Multiply 4x + 3y = 12 by 3. It becomes 12x + 9y = 36.

12x + 9y = 36

+-3x - 9y = 18

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9x = 54

x = 6

To solve for y, substitute x = 6 into one of the equations.

12(6) + 9y = 36

72 + 9y = 36

9y = -36

y = -4