SOLUTION: the difference between two numbers is three, two times the first number plus the second number is 3, solve by graphing

Algebra ->  Linear-equations -> SOLUTION: the difference between two numbers is three, two times the first number plus the second number is 3, solve by graphing      Log On


   

Question 515358: the difference between two numbers is three, two times the first number plus the second number is 3, solve by graphing
Answer by oberobic(2304) About Me  (Show Source):
You can put this solution on YOUR website!
x -y = 3
so
x = y+3
and
y = x-3
.
2x + y = 3
so
y = -2x +3
.
So, we have two linear equations.
.
+graph%28500%2C500%2C-5%2C5%2C-5%2C5%2Cx-3%2C-2%2Ax%2B3%29+
.
The intercept is (2,-1).
.
Check to ensure this is the solution for both equations.
.
y = x-3
y = 2-3
y = -1
.
y = -2(2) +3
y = -4 +3
y = -1
.
You also could set the two equations equal to one another.
x-3 = -2x +3
3x -3 = 3
3x = 6
x = 2
.
Substitute x=2 into either equation to find 'y'
.
2-3 = -1
.
Of course you could solve by adding the equations:
.
x -y = 3
2x + y = 3
------------
3x = 6
x = 2
.
And substitute to find 'y'
.
Done.