Solve for xy in Algebra 1: 3x+4y=7 and 2y=6x+6

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    Algebra Algebra 1
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Homework Help Overview

The discussion revolves around solving a system of linear equations in algebra, specifically the equations 3x + 4y = 7 and 2y = 6x + 6. Participants are attempting to find the product xy based on these equations.

Discussion Character

  • Exploratory, Problem interpretation, Assumption checking

Approaches and Questions Raised

  • Participants are exploring various methods to manipulate the equations, including adding them to eliminate variables. There is confusion regarding the steps taken and the resulting values for y and x.

Discussion Status

Some participants have provided guidance on how to approach the problem, while others express confusion about the process and results. There is a recognition of the correct value for y, but uncertainty remains about how to proceed to find x and ultimately xy.

Contextual Notes

One participant mentions being in 7th grade and learning from a book, indicating a potential gap in understanding foundational concepts. There is also a discrepancy in the expected answer, which adds to the confusion.

staples82
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If 3x+4y=7 and 2y=6x+6, then what is xy?


3X+4y=7
-6X+2y=6

(2)3X+4y=7 which goes to 6X+8Y=14

I cross the X out, subtract and get 6y=8

then I got 4/3
and final answer i got was 20/3

HOWEVER, the answer says is is -2/3 ... I don't understand how that is the answer...

Please Help!
 
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You should add them.y=20/10=2.

Daniel.
 
i don't understand...
 
[tex]\left\{\begin{array}{c} 6x+8y=14 \\ -6x+2y=6 \end{array} \right[/tex]

As i said before,add the two equations,so you'd eliminate "x".

Daniel.
 
yeah, then i got 6y=8
 
Why?Don't ypu know what "addition" or "adding" means...?

Daniel.
 
oh, my bad ...2, so do I plug it back in, sorry I am going into 7th grade, learning this from a book.

update: ok I understand what you said, now I have y=2...
 
Last edited:
Yes, you are correct that y=2. Now as you said plug it back into find the unknown x.

[tex]3x + 4y = 7[/tex]

You know what to do.

Jameson
 
thank you, dextercioby and Jameson, I understand the problem now.
 

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