College Algebra (6th Edition)

Published by Pearson
ISBN 10: 0-32178-228-3
ISBN 13: 978-0-32178-228-1

Chapter P - Prerequisites: Fundamental Concepts of Algebra - Exercise Set P.4: 35

Answer

$25-49x^2$ Note that standard form would list the variables first in decreasing order of exponent, so another way to write this answer is $-49x^2+25$.

Work Step by Step

$$(5-7x)(5+7x)$$ $$=(5\times 5)+(5\times 7x)+(-7x\times 5)+(-7x\times 7x)$$ $$=25+35x-35x-49x^2$$ $$=25-49x^2$$ Note that standard form would list the variables first in decreasing order of exponent, so another way to write this answer is: $$-49x^2+25$$
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