Question 145192
I'll do the first one to get you started






Start with the given system of equations:


{{{-x+y=-1}}}

{{{x+y=3}}}





In order to graph these equations, we need to solve for y for each equation.




So let's solve for y on the first equation


{{{-x+y=-1}}} Start with the given equation



{{{y=-1+x}}} Add {{{ x}}} to both sides



{{{y=+x-1}}} Rearrange the equation



Now lets graph {{{y=x-1}}} (note: if you need help with graphing, check out this <a href=http://www.algebra.com/algebra/homework/Linear-equations/graphing-linear-equations.solver>solver</a>)



{{{ graph( 600, 600, -10, 10, -10, 10, x-1) }}} Graph of {{{y=x-1}}}




So let's solve for y on the second equation


{{{x+y=3}}} Start with the given equation



{{{y=3-x}}}  Subtract {{{ x}}} from both sides



{{{y=-x+3}}} Rearrange the equation




Now lets add the graph of {{{y=-x+3}}} to our first plot to get:


{{{ graph( 600, 600, -10, 10, -10, 10, x-1,-x+3) }}} Graph of {{{y=x-1}}}(red) and {{{y=-x+3}}}(green)


From the graph, we can see that the two lines intersect at the point (2,1)