#### Answer

$-(x+5)(x-8)$

#### Work Step by Step

We start by factoring out -1. We have $-x^2+3x+40=-(x^2-3x-40)$
The factor pairs of -40 are
1 and -40, -1 and 40
2 and -20, -2 and 20
4 and -10, -4 and 10
5 and -8, -5 and 8
5 and -8 add up to -3

Published by
Prentice Hall

ISBN 10:
0133186024

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

$-(x+5)(x-8)$

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