How do you graph #x+2y >=-8# on a graphing calculator?

1 Answer

This depends on the capabilities of your calculator, however, converting the equation to a y=... format will work on many (if not all) graphing calculators.

Explanation:

first, lets start making the inequality a bit simpler for the calculator to understand by converting it to a function.

#x+2y=-8#

Then using basic algebra, we can move this to a calculators preferred form by solving for y.

#2y=-8-x#
#y=-(8/2)-(x/2)#
#y=-4-0.5x#

Once you plot this function, you can visualize the range of values where #y>=-4-0.5x#
These will be any point on the x,y plane that have a y-coordinate greater than that given by the function, creating a shaded area of infinite points vertically above the line.

For example, (2,1) will be in the shaded area above the line as the value of the function at x=2 (which is y=-5) will be less than the y-value associated with the point (2,1) (which is y=-1).