3x+4y=-3 x+2y-5

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embizze's profile pic

embizze | High School Teacher | (Level 1) Educator Emeritus

Posted on

Solve the system :

3x+4y=-3
x+2y=-5

We can solve using the combinations method:

Multiply the second equation by -2, then add the resulting equation to the first equation:

3x+4y=-3
-2x-4y=10
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x=7

Substituting x=7 into the first equation we get:

3(7)+4y=-3

4y=-24

y=-6

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The solution is (7,-6)

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Check: 3(7)+4(-6)=21-24=-3 and 7+2(-6)=7-12=-5

The graphs:

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tonys538 | Student, Undergraduate | (Level 1) Valedictorian

Posted on

The system of equations 3x+4y=-3 and x+2y=-5 has to be solved.

From the equation x+2y=-5, express x in terms of y.

x+2y=-5

x = -5 - 2y

Now substitute this for x in 3x+4y=-3

3*(-5 - 2y) + 4y = -3

-15 - 6y + 4y = -3

-2y = 12

y = -6

x = -5 - 2y = -5 - (-6*2) = -5 + 12 = 7

The solution of the given system of equations is x = 7 and y = -6

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