Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 7 - Section 7.6 - Radical Equations - Exercise Set - Page 560: 50

Answer

The $x$ intercept is $x= 2$.

Work Step by Step

Given $$ f(x)=\sqrt{2 x-3}-\sqrt{2 x}+1$$ The x intercept of a function can be found by setting the function to zero and solving for the value(s) of $x$ that makes the function equal to zero. Hence \begin{equation} \begin{aligned} f(x)&=0\\ \sqrt{2 x-3}-\sqrt{2 x}+1&=0\\\ \sqrt{2 x-3}+1& =\sqrt{2 x} \\ \left(\sqrt{2 x-3}+1\right)^2& =\left(\sqrt{2 x}\right)^2\\ 2 x-3+2\sqrt{2 x-3}+1& =2x\\ 2\sqrt{2 x-3}& =2x-2 x+2\\ 2\sqrt{2 x-3}& =2\\ \sqrt{2 x-3}& =1\\ \left(\sqrt{2 x-3}\right)^2& =1\\ 2x-3&= 1\\ 2x&= 1+3\\ 2x&= 4\\ x&= 2 \end{aligned} \end{equation} Check: In line 3, I have used the fact that $(a-b)^2= a^2-2ab+b^2$ to expand $\left(\sqrt{2 x-3}+1\right)^2= 2 x-3+2\sqrt{2 x-3}+1$. \begin{equation} \begin{aligned} f(2)&= \sqrt{2 \cdot 2-3}-\sqrt{2 \cdot 2}+1\\ &= \sqrt{4-3}-\sqrt{4}+1\\ &=1-2+1\\ &= 0 \end{aligned} \end{equation}
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