#### Answer

$-(x-4)(x+5)$

#### Work Step by Step

We start by factoring out -1. We have $-x^2-x+20=-(x^2+x-20)$
The factor pairs of -20 are
1 and -20, -1 and 20
2 and -10, -2 and 10
4 and -5, -4 and 5
-4 and 5 add up to 1.

Published by
Prentice Hall

ISBN 10:
0133186024

ISBN 13:
978-0-13318-602-4

$-(x-4)(x+5)$

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