Finding the ordered pair: 6x + 7y - 7 (1), x= 6-7y (2)

Simplificatation, evaluation, linear equations, linear graphs, linear inequalities, basic word problems, etc.
needmathhelp
Posts: 2
Joined: Wed Jul 22, 2009 4:59 am
Location: Utah
Contact:

Finding the ordered pair: 6x + 7y - 7 (1), x= 6-7y (2)

Postby needmathhelp » Thu Jul 23, 2009 11:35 pm

6x + 7y - 7 (1)

x= 6-7y (2)

What is the ordered pair? :D

User avatar
stapel_eliz
Posts: 1738
Joined: Mon Dec 08, 2008 4:22 pm
Contact:

Postby stapel_eliz » Fri Jul 24, 2009 12:05 am

needmathhelp wrote:6x + 7y - 7 (1)
x= 6-7y (2)

What is the ordered pair?

This system is set up for solving by "substitution". So plug the expression for "x" in the second equation (being the right-hand side of that equation) in for "x" in the first equation, and solve (if possible) for the value of y.

What do you get? :wink:

needmathhelp
Posts: 2
Joined: Wed Jul 22, 2009 4:59 am
Location: Utah
Contact:

Re: Finding the ordered pair: 6x + 7y - 7 (1), x= 6-7y (2)

Postby needmathhelp » Fri Jul 24, 2009 1:56 am

6x + 7y - 7 (1)
x= 6-7y (2)

What is the ordered pair?
6(x=6-7y) + 7y -7
6x = 36- 42y + 7y- 7
6x =29 -35y
This is where I got stuck.

User avatar
stapel_eliz
Posts: 1738
Joined: Mon Dec 08, 2008 4:22 pm
Contact:

Postby stapel_eliz » Fri Jul 24, 2009 3:57 pm

needmathhelp wrote:6x + 7y - 7 (1)

By the way, I'm assuming that the above is a typo, and that the "minus" sign is supposed to be an "equals" sign.

needmathhelp wrote:6(x=6-7y) + 7y -7

Please review the lesson (provided in the link, earlier) and re-read the instructions in the previous reply. You are not supposed to plug the entire second equation in for the one variable; you are supposed to "substitute" the expression that "x=" (that is, the expression on the other side from "x") in for "x" in the first equation, so that you have only one variable, not two, and only one "equals" sign.


Return to “Beginning Algebra”