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

In summary, the conversation revolved around solving the equation 3x+4y=7 and 2y=6x+6 to find the value of xy. The participants discussed adding the two equations to eliminate the variable x and then plugging in the value of y to find the value of x. The final answer was determined to be -2/3, which caused confusion for one of the participants. After further clarification, they all agreed on the solution.
  • #1
staples82
17
0
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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  • #3
i don't understand...
 
  • #4
[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.
 
  • #5
yeah, then i got 6y=8
 
  • #6
Why?Don't ypu know what "addition" or "adding" means...?

Daniel.
 
  • #7
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:
  • #8
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
 
  • #9
thank you, dextercioby and Jameson, I understand the problem now.
 

1. What is the process for solving for xy in Algebra 1?

The process for solving for xy in Algebra 1 involves using the given equations to eliminate one variable and then substituting the remaining variable into the other equation to solve for its value. In this case, we can use the second equation to solve for y and then substitute that value into the first equation to solve for x.

2. How do I eliminate one variable in the given equations?

To eliminate one variable, you can use the method of substitution or elimination. In substitution, you solve for one variable in one equation and then substitute its value into the other equation. In elimination, you manipulate the equations to add or subtract them to eliminate one variable.

3. Can I solve for xy if there are more than two equations given?

Yes, you can solve for xy if there are more than two equations given. You will need to use the elimination method to eliminate one variable at a time until you have two equations with two variables remaining, and then solve for those variables.

4. What is the importance of solving for xy in Algebra 1?

Solving for xy in Algebra 1 helps in finding the values of two variables in a system of equations. This is useful in solving real-world problems such as finding the intersection point of two lines or finding the solution to a system of equations in physics or chemistry.

5. What are some tips for solving for xy in Algebra 1?

Some tips for solving for xy in Algebra 1 include carefully reading and understanding the given equations, choosing the most efficient method of elimination, and checking your answer by substituting the values of x and y into the original equations to ensure they satisfy both equations.

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