How do you solve #x+y=3#, #y=2x15# by graphing?
2 Answers
Explanation:
We can graph them like this:

#x+y=3# can be graphed by seeing that when#x=0, y=3# and when#x=3, y=0# . Plot those two points and draw a line through them. 
y=2x15 can be graphed by first plotting the yintercept (
#0,15# ) and then using the slope of 2 to move up two points and to the right 1 (#1,13# ), plotting those two points and drawing a line through them.
Together, they look like this:
graph{(y+x3)(y2x+15)=0 [3.22, 14.56, 8.36, 0.53]}
And this gives us the point
Explanation:
To solve two linear equations in two variables, what you need is to draw their graph and as they represent two lines, look for their point of intersection, which gives the solution of the equations.
To draw the graph of lines, select three pair of solutions (as it is a linear equation two should satisfy, but we have mentioned three to confirm we are on right track for graph), which when represented on a Cartesian graph, will give the graph of the line. It would be preferable, if these points are wide apart.
For example, for first equation
graph{x+y=3 [9.67, 10.33, 3.36, 6.64]}
For second equation, we can again choose
graph{2x15 [36.55, 43.45, 20.32, 19.68]}
When the two graphs are drawn on the same graph, lines intersect at
graph{(x+y3)(y2x+15)=0 [5.78, 14.22, 5.64, 4.36]}