How do you find the point of intersection for x+y=3x+y=3 and 2x-y= -32xy=3?

2 Answers
Jun 26, 2015

The given lines intersect at (0,3)(0,3)

Explanation:

[1]color(white)("XXXX")XXXXx+y=3x+y=3
[2]color(white)("XXXX")XXXX2x-y= -32xy=3

add [1] and [2]
[3]color(white)("XXXX")XXXX3x = 03x=0
[4]color(white)("XXXX")XXXXx=0x=0

substituting 00 for xx in [1]
color(white)("XXXX")XXXX0 + y = 30+y=3
color(white)("XXXX")XXXXy=3y=3

Jun 26, 2015

I found the point of intersection of coordinates:
x=0x=0
y=3y=3

Explanation:

You basically solve the System of the two equations trying to find values of xx and yy that satisfy both equations simultaneously.
From the first you can isolate xx as:
x=3-yx=3y
now you can substitute this xx into the second equation and find yy as:
2(3-y)-y=-32(3y)y=3
6-2y-y=-362yy=3
-3y=-93y=9
y=3y=3
substitute back this value into the first equation to find xx:
x=3-3=0x=33=0