College Algebra (10th Edition)

Published by Pearson
ISBN 10: 0321979478
ISBN 13: 978-0-32197-947-6

Chapter 1 - Review Exercises - Page 145: 18

Answer

$x_1=5$ $x_2=41$

Work Step by Step

Square each side: $(\sqrt{2x-1}-\sqrt{x-5})^2=3^2$ $2x-1-2\sqrt{2x-1}\sqrt{x-5}+x-5=9$ Add same term variables and move the radicals to the right side: $3x-6-2\sqrt{2x-1}\sqrt{x-5}-9+2\sqrt{2x-1}\sqrt{x-5}=9-9+2\sqrt{2x-1}\sqrt{x-5}$ $3x-15=2\sqrt{2x-1}\sqrt{x-5}$ Square each side again: $(3x-15)^2=(2\sqrt{2x-1}\sqrt{x-5})^2$ $9x^2-45x-45x+225=4(2x-1)(x-5)$ Simplify: $9x^2-90x+225=4(2x^2-10x-x+5)$ $9x^2-90x+225=4(2x^2-11x+5)$ $9x^2-90x+225=8x^2-44x+20$ $9x^2-90x+225-(8x^2-44x+20)=8x^2-44x+20-(8x^2-44x+20)$ $x^2-46x+205x=0$ Breaking down 205, we find that it only has two multiples, 41 and 5, which makes factoring possible: $(x-5)(x-41)=0$ And we get two solutions: $x_1-5=0$ $x_1=5$ $x_2-41=0$ $x_2=41$ We insert them into the original equation to find extraneous solutions: $\sqrt{2(x_1)-1}-\sqrt{(x_1)-5}=3$ $\sqrt{2(5)-1}-\sqrt{(5)-5}=3$ $\sqrt{10-1}-\sqrt{0}=3$ $\sqrt{9}-0=3$ $3=3\checkmark$ $\sqrt{2(x_2)-1}-\sqrt{(x_2)-5}=3$ $\sqrt{2(41)-1}-\sqrt{(41)-5}=3$ $\sqrt{82-1}-\sqrt{36}=3$ $\sqrt{81}-6=3$ $9-6=3$ $3=3\checkmark$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.