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September 18, 2014

September 18, 2014

Posted by **Joel** on Tuesday, February 22, 2011 at 11:29am.

-3x + 4y = -19.5

-3x + y = -10.5

- algebra -
**Betty**, Tuesday, February 22, 2011 at 4:05pm-3x + 4y = -19.5

-3x + y = -10.5

-3x + y = -10.5

+3x +3x

y = 3x - 10.5

-3x +4y = -19.5

-3x +4(3x -10.5) = -19.5

-3x + 4(3x) + 4(-10.5) = -16.5

-3x +12x - 42 = -16.5

9x - 42 = -16.5

+42 = + 42

9x = 42 - 19.5

9x = 22.5

9x / 9x= 22.5 / 9

x = 2.5

Plug x into the original equation to solve for y

y = 3x - 10.5

y = 3(2.5) - 10.5

y = 7.5 - 10.5

y = -3

Solution: (2.5, -3)

Check

-3x + 4y = -19.5 -3x + y = -10.5

-3(2.5) + 4(-3) = - 19.5 -3(2.5) + -3 = -10.5

-7.5 + (-12) = -19.5 -7.5 + (-3) = -10.5

-19.5 = -19.5 -10.5 = -10.5

True True

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