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Solve the system of equations 6x+3y=9 and -9x−2y=9 by combining the equations.

User Tams
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1 Answer

3 votes

Answer:

x = -3

y = 9

Explanation:

6x + 3y = 9 ⇒ ( 1 )

Divide the whole equation by 3.

2x + y = 3 ⇒ ( 2 )

-9x - 2y = 9 ⇒ ( 3 )

Let us take equation (2) and make y the subject of the equation.

2x + y = 3

y = 3 - 2x ⇒ ( 4 )

Now let us take equation (3) and find the value of x.

For that, we can replace y with ( 3 - 2x ).

Let us solve it now.

-9x - 2y = 9

-9x - 2 ( 3 - 2x ) = 9

-9x -6 + 4x = 9

-5x - 6 = 9

-5x = 9 + 6

-5x = 15

Divide both sides by (-5).

x = -3

And now let us take equation (4) to find the value of y.

For that, we can replace x with -3.

Let us solve it now.

y = 3 - 2x

y = 3 - 2 × -3

y = 3 + 6

y = 9

User Evi
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