Algebra help with system of equations

Algebra
Tutor: None Selected Time limit: 1 Day

It goes like this:

2x+y=6 and 7x+2y=4

After you solve, they then give you 4 choices for which one has the same answer:

A: 2x+y=6 and 3x-y=10

B: 7x+2y=4 and 6x-2y=10

C: 2x+y=6 and -3x-y=-9

and

D: 7x+2y=4 and -4x-2y=-12

May 6th, 2015

2x + y = 6

7x + 2y = 4


Multiply the first equation by -2 on both sides

-2(2x + y) = -2*6

-4x - 2y = -12 

This represents the same line as first equation.


So the answer is

D:  7x + 2y = 4   and -4x - 2y = -12


May 6th, 2015

What I had actually meant was 'which system has the same *solution* as the first one.

May 6th, 2015

And the answers are x and y.

May 6th, 2015

They include x and y is what I meant.

May 6th, 2015

Yes the equations in option D) have the same solution as the ones in the question as both the system of equations represent the same set of lines.

May 6th, 2015

Oh. I see now. Thanks!

May 6th, 2015

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