# Graph Linear Equation X+Y=5

• Nov 25th 2007, 05:58 PM
MathMack
Graph Linear Equation X+Y=5
I got two, X+Y=5 and X - Y=5

Where do I start and how do I do these. Thanks as always!
• Nov 25th 2007, 06:03 PM
Jhevon
Quote:

Originally Posted by MathMack
I got two, X+Y=5 and X - Y=5

Where do I start and how do I do these. Thanks as always!

the nice thing about straight lines is that you only need two points to graph them. the intercepts are usually good points to graph.

begin by solving for y, we get: y = 5 - x

the y-intercept is the lone constant, so the line passes through (0,5)

for the x-intercept, set y = 0 and solve for x. we find that the x -intercept is 5 as well, so the line passes through (5,0)

so plot these two points on the axis and draw a straight line through them and you're done.

now, do the other
• Nov 25th 2007, 06:11 PM
MathMack
for the 2nd part I get y=-1+x correct?
• Nov 25th 2007, 06:40 PM
Jhevon
Quote:

Originally Posted by MathMack
for the 2nd part I get y=-1+x correct?

i thought it was 5? where did 1 come from?

it is customary to write the positive value first, so write y = x - 1.

if both values are positive, it is customary to write the x-term first, e.g. y = x + 1