Answer
$y=7$ or $y=-3$.
Work Step by Step
By factorization, we have
$$y^2 -4y-21=(y-7)(y+3)=0.$$
Then we have
$$(y-7) =0, \quad \text{or} \quad (y+3)=0$$
that is $y=7$ or $y=-3$.
Elementary Technical Mathematics
by Nelson, Robert; Eren, Dale;
Published by
Brooks Cole
ISBN 10:
1285199197
ISBN 13:
978-1-28519-919-1
Chapter 11 - Section 11.1 - Solving Quadratic Equations by Factoring - Exercise - Page 364: 13
Update this answer!
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.
