How do you solve y=2x-1 and y=x+2?

1 Answer
Aug 5, 2016

First part of the calculation given in detail so that you can see the method more clearly. The second part uses shortcuts.

Point of intersection P1(x,y)=(3,5)

Explanation:

Given:

y=2x1....................Equation(1)
y=x+2.....................Equation(2)
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Consider equation 2

Subtract 2 from both sides

y2=x+22

y2=x..........................Equation(3)
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Using equation(3) substitute for x in equation(1)

y=2(y2)1

y=2y41

y=2y5

Subtract y form both sides

yy=2yy5

0=y5

Add 5 to both sides

y=5
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Substitute y=5 into either equation(1) or (2). I chose (2)

y=x+2 5=x+2

x=3

Tony B