Question

Solve by Graphing:

2x +2y = -8

y= 2x + 2

Answer 1

2x+2y=-8. Find the intercepts: solve when y=0 to get 2x=-8, x=-4 is the x intercept (-4,0); solve when x=0 to get 2y=-8, y=-4 is the y intercept (0,-4). Draw a line through these intercept points.

Similarly draw y=2x+2 to get the x intercept at (-1,0) and y intercept (0,2). Draw a line through the intercepts.

Where the lines cross is the solution. The lines should cross at (-2,-2) when the x and y values coincide.

2x+2y=-8, so x+y=-4 and y=-4-x; and y also equals 2x+2, so:

-4-x=2x+2, -6=3x, -2=x so x=-2 and y=2(-2)+2=-4-(-2)=-2, that is, the point (-2,-2).