How do you solve abs(7-y)=4|7y|=4?

1 Answer
Apr 4, 2018

y = 3 and y = 11

Explanation:

Because we are taking the absolute value of 7-y7y, we set up two equations that correspond to the negative and positive outcomes of |7-y||7y|

7-y = 47y=4
and
-(7-y) = 4(7y)=4

This is because taking the absolute value of both equations will yield the same answer. Now all we do is solve for y in both cases

7-y=4; y = 37y=4;y=3

and

-7+y=4; y = 117+y=4;y=11

We can plug both values into the original function to demonstrate this.

|7-(3)| = 4|7(3)|=4

|7-(11)|=4|7(11)|=4

Both cases are true, and we have two solutions for y