Algebra 2 Common Core

Published by Prentice Hall
ISBN 10: 0133186024
ISBN 13: 978-0-13318-602-4

Chapter 6 - Radical Functions and Rational Exponents - 6-5 Solving Square Root and Other Radical Equations - Practice and Problem-Solving Exercises - Page 395: 27

Answer

$x = 1$

Work Step by Step

We need to get rid of the fractional exponents to be able to solve this equation; therefore, we will multiply by the reciprocal of the fractional exponent $1/2$, which is $2$. We will now square both sides of the equation: $((5 - x)^{1/2})^2 = (x + 1)^2$ Simplify the equation: $5 - x = (x + 1)(x + 1)$ $5 - x = (x)(x) +1x + 1x + (1)(1)$ $5 - x = x^2 + 2x + 1$ Rewrite the equation so one side is $0$: $0=x^2 + 2x + 1 - 5 + x\\ 0=x^2+3x-4\\ x^2+3x-4=0$ Factor the trinomial: $(x-1)(x+3)=0$ Use the Zero-Product Property by equating each factor to $0$, then solve each equation. First factor: $x - 1 = 0$ $x = 1$ Second factor: $x + 4 = 0$ $x = -4$ To check if our solutions are correct, we plug our solutions back into the original equation to see if the left and right sides equal one another. Let's plug in $x = 1$ first: $(5 - 1)^{1/2} = 1 + 1$ Evaluate parentheses first, according to order of operations: $(4)^{1/2} = 1 + 1$ Let's evaluate the exponent next: $2 = 1 + 1$ Now add the right side of the equation: $2 = 2$ The left and right sides are equal; therefore, this solution is correct. Let's check $x = -4$: $(5 - (-4))^{1/2} = -4 + 1$ Evaluate parentheses first, according to order of operations: $(9)^{1/2} = -4 + 1$ Let's evaluate the exponent next: $3 = -4 + 1$ Now add the right side of the equation: $3 = -3$ The left and right sides are not equal; therefore, this is an extraneous solution. The solution is $x = 1$.
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