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: 50

Answer

$81-90x+25x^2$ Note: standard form lists variables first in decreasing order of exponent, so this answer could also be written as: $25x^2-90x+81$.

Work Step by Step

$$(9-5x)^2$$ $$=(9-5x)(9-5x)$$ $$=(9\times 9)+(9\times (-5x))+(-5x\times 9)+(-5x\times (-5x))$$ $$=81-45x-45x+25x^2$$ $$=81-90x+25x^2$$ Note: standard form lists variables first in decreasing order of exponent, so this answer could also be written as: $$25x^2-90x+81$$
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