Homework Help: math

Posted by deedee on Tuesday, January 6, 2009 at 2:23pm.

Can someone please check my work?

Solve using substitution method

1. 3x+2y=12
x=52-6y
answer:-40.8 I am pretty sure that one is wrong.

Solve using elimination method

2. 2r-7s=-31
7r+2s=24
answer: (230/53,-468/53)

3.3x+4y=3
6x+8y=6
answer: No answer. problems eliminate eachother

math - Damon, Tuesday, January 6, 2009 at 2:26pm
3(52-6y) + 2 y = 12
156 - 18 y + 2 y = 12
-16 y = -144
y = 9
x = 52 - 6(9) = 52 - 54 = -2
math - deedee, Tuesday, January 6, 2009 at 2:39pm
Thank you Damon!
Can you help me with the formula to solve by elimination?
math - Damon, Tuesday, January 6, 2009 at 2:44pm
3x+2y=12
x=52-6y multiply everything by 3 on this line

3x+2y=12
3 x = 156 - 18y
---------------- subtract
0 x + 2y = 12 -156 + 18 y
0 = - -144 + 16 y
y = 144/16 = 9 again
math - Anonymous, Sunday, May 16, 2010 at 10:29pm
2r-7s=0
7r+2s=53
math - mani, Tuesday, December 21, 2010 at 8:58pm
6,174,000,000

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