SOLUTION: how to solve using substitution y=2x-3 and y=-x-3

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: how to solve using substitution y=2x-3 and y=-x-3      Log On


   

Question 261879: how to solve using substitution
y=2x-3 and y=-x-3
Found 3 solutions by drk, richwmiller, solver91311:
Answer by drk(1908) About Me  (Show Source):
You can put this solution on YOUR website!
To solve using substitution, we need to solve an equation for y. We already have that in the two given equations:
(i) y=2x-3
(ii) y=-x-3
set them equal to get
(iii) 2x-3+=+-x-3
add x to both sides to get
(iv) 3x-3+=+-3
add 3 to both sides to get
(v) 3x+=+0
so,
x = 0
and
y = -3

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
take -x-3 and substitute it for the y of the first equation to get
-x-3=2x-3
add x to both sides
-3=3x-3
add 3 to both sides
0=3x
x=0
y=-3
(0,-3)

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


You have two equations each of which describe the value of in terms of .

Start with the first equation:



In place of the in that equation, substitute the expression in from the other equation:



Now just solve the single equation in one variable. Once you have a value for the variable, substitute that back into either equation to determine the value for . The solution set will be a single ordered pair of the form such that the coordinates will make true statements out of either given equation.

John