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March 28, 2015

Posted by **HELP me please asap!!** on Monday, January 24, 2011 at 12:45am.

*4y=15-3x

2y=3x+21

*4x=5y-14

y=-6x-9

*5x=4y-30

2x=3y=-12

*2/3y=10+4x

5x=1/3y-8

use linear combinations to solve the system of linear equations

thank you!!!

- math -
**MathMate**, Monday, January 24, 2011 at 9:03am4y=15-3x ...(1)

2y=3x+21 ...(2)

Rewrite in standard form:

3x+4y-15=0....(1a)

3x-2y+21=0....(2a)

Subtract 2a from 1a to get

0x+6y - 36 = 0

from which y=6

Add 2(2a) to (1a) to get

9x+0y+27 = 0

from which x = -3

Check:

4y=24, 15-3x=24 OK

2y=12, 3x+21=12 OK

You can proceed the same way for the remaining problems. Post for answer verification if you wish, but it should not be necessary because a check with the original equations should have been done as in the example.

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