How do you graph #-3y<21# on the coordinate plane?

1 Answer
smendyka
Oct 29, 2017

See a solution process below:

Explanation:

Divide each side of the inequality by #color(blue)(-3)# to solve for #y# while keeping the inequality balanced. However, because we are multiplying or dividing an inequality by a negative number we must reverse the inequality operator:

#(-3y)/color(blue)(-3) color(red)(>) 21/color(blue)(-3)#

#(color(blue)(cancel(color(black)(-3)))y)/cancel(color(blue)(-3)) color(red)(>) -7#

#y > -7#

To graph this we will draw a horizontal at #-7# on the vertical axis.

The line will be a dashed line because the inequality operator does not contain an "or equal to" clause.

We will shade above the the line because the inequality operator does contain a "greater than" clause:

graph{y>=-7 [-15, 15, -12.5, 12.50]}

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