How do you solve -7abs(-3-3r)=-21?

1 Answer
Aug 25, 2016

The solution set is {0, -2}.

Explanation:

Let's first isolate the absolute value on one side of the equation.

|-3 - 3r| = -21/-7

|-3 - 3r| = 3

Now, when dealing with absolute value equations, we must consider two scenarios.

A: The absolute value is positive.

-3 - 3r = 3

-3r = 6

r = -2

B: The absolute value is negative

-(-3 - 3r) = 3

3 + 3r = 3

3r = 0

r = 0

The solutions are r = 0 and r = -2. However, let's check that the solutions satisfy the original equation before stating the solution set.

-7|-3 - 3(0)| =^? -21

-7|-3| =^? -21

-7(3) = -21

AND

-7|-3 - (-3 xx -2)| =^? -21

-7|3| =^? -21

-7(3) = -21

Hence, neither of the solutions are extraneous. The solution set is {0, -2}.

Hopefully this helps!