Algebra 1

Published by Prentice Hall
ISBN 10: 0133500403
ISBN 13: 978-0-13350-040-0

Chapter 8 - Polynomials and Factoring - 8-7 Factoring Special Cases - Practice and Problem-Solving Exercises - Page 515: 42



Work Step by Step

The student made the error that they did not simplify the $9x^{2}$ as in a difference of squares formula both first and last terms are simplified. The difference of squares formula is: $(a-b) (a+b) = a^{2} - b^{2}$ = $9x^{2}$ - 49 *** Take the square root of $9x^{2}$ which is 3x. Becuase 3x × 3x= $9x^{2}$ *** Take the square root of 49 which is 7. Becuase 7 × 7= 49 = $(3x)^{2}$ - $(7)^{2}$ In the given formula let 3x represents a and 49 represents b. $(3x)^{2}$ - $(7)^{2}$ = (3x+7)(3x-7)
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