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September 21, 2014

September 21, 2014

Posted by **Laruen** on Tuesday, January 29, 2013 at 8:54pm.

Systems of Equation

2x = y

4x - y = -2

please help!!!!!

- Math 8R - HELP! -
**Reiny**, Tuesday, January 29, 2013 at 9:09pmI would use substitution

sub the 1st into the 2nd

4x - y = -2

4x - (2x) = -2

2x = -2

x = -1

then back into the first

y = 2x

y = 2(-1) = -2

- Math 8R - HELP! -
**Laruen**, Tuesday, January 29, 2013 at 9:25pmthank you ....

2x + 4y = 24

x - 2y = -8

my mom tried helping me but didn't understand it....

- Math 8R - HELP! -
**Reiny**, Tuesday, January 29, 2013 at 9:31pmFor your second example I would use substitution again

Notice that in the second equation the x variable is all by itseld, that is, it is 1x understood.

That is the key.

look for a variable like that and solve for it

x - 2y = -8

x = 2y - 8

now sub that x value of (2y-8) into the other equation

2(2y-8) + 4y = 24

4y - 16 + 4y = 24

8y = 24 + 16

8y = 40

y = 40/8 = 5

now plug that into

x = 2y-8

x = 2(5)-8 = 2

so x=2, y=5

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