Substitution

Jennifer3

New member
Joined
Oct 27, 2005
Messages
6
Could someone show me how to do this? The instructions say "Solve each of the following systems of equations by substitution. Check the solution by replacing the ordered pair into both equations." And this is the first problem
y=3x
x+y=8
My guess is that it would be like this...
For Y: y=3(0)
y=0
For X: 0=3x
x=3 (that may be wrong)

For Y: 0+y=8
y=8
For X: x+0=8
x=8
This is what we were doing earlier, but I don't understand how we're supposed to check the solution
 
Ok that was totally wrong I got confused by something else we've been doing. Is it like this?
x+3x=8
4x=8
x=2
But then how do I check the solution? Can someon please tell me if I'm getting close?
 
Your second post shows good progress toward to solution. Now plug "2" in for "x" in either of the original equations, and solve for the value of y. The (x, y) point you get is the solution to the system.

To check your solution, plug your x- and y-values into the original equations, and make sure they both "check"; that is, verify that they both evaluate to true statements.

Eliz.

P.S. Thank you for showing your work and reasoning!! :D
 
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