Algebra 2 Common Core

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

Chapter 4 - Quadratic Functions and Equations - 4-7 The Quadratic Formula - Practice and Problem-Solving Exercises - Page 245: 20

Answer

$x=\dfrac{1-\sqrt{7}}{2} \text{ and } x=\dfrac{1+\sqrt{7}}{2} $

Work Step by Step

Using the properties of equality, the given equation, $ 2x(x-1)=3 ,$ is equivalent to \begin{align*} 2x(x)+2x(-1)&=3 &\text{ (use Distributive Property)} \\ 2x^2-2x&=3 \\ 2x^2-2x-3&=0 \end{align*} In the equation above, $a= 2 ,$ $b= -2 ,$ and $c= -3 .$ Using the Quadratic Formula which is given by $x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a},$ then \begin{align*}\require{cancel}x&= \dfrac{-(-2)\pm\sqrt{(-2)^2-4(2)(-3)}}{2(2)} \\\\&= \dfrac{2\pm\sqrt{4+24}}{4} \\\\&= \dfrac{2\pm\sqrt{28}}{4} \\\\&= \dfrac{2\pm\sqrt{4\cdot7}}{4} \\\\&= \dfrac{2\pm2\sqrt{7}}{4} \\\\&= \dfrac{\cancel2^1\pm\cancel2^1\sqrt{7}}{\cancel4^2} &\text{ (divide by $2$)} \\\\&= \dfrac{1\pm\sqrt{7}}{2} \end{align*} Hence, the solutions are$ x=\dfrac{1-\sqrt{7}}{2} \text{ and } x=\dfrac{1+\sqrt{7}}{2} .$
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