Big Ideas Math - Algebra 1, A Common Core Curriculum

Published by Big Ideas Learning LLC
ISBN 10: 978-1-60840-838-2
ISBN 13: 978-1-60840-838-2

Chapter 9 - Solving Quadratic Equations - 9.5 - Solving Quadratic Equations Using the Quadratic Formula - Exercises - Page 521: 37

Answer

The solutions are $x=\frac{4}{5}$ and $x=\frac{1}{2}$.

Work Step by Step

The given equation is $\Rightarrow -10x^2+13x=4$ Subtract $4$ from each side. $\Rightarrow -10x^2+13x-4=0$ The equation is easily factorable. So, solve by factoring. $\Rightarrow -10x^2+13x-4=0$ Rewrite $13x$ as $8x+5x$. $\Rightarrow -10x^2+8x+5x-4=0$ Group the terms. $\Rightarrow (-10x^2+8x)+(5x-4)=0$ Factor each group. $\Rightarrow -2x(5x-4)+1(5x-4)=0$ Factor out $(5x-4)$. $\Rightarrow (5x-4)(-2x+1)=0$ Use zero-product property. $\Rightarrow 5x-4=0$ or $-2x+1=0$ Solve for $x$. $\Rightarrow x=\frac{4}{5}$ or $x=\frac{1}{2}$ Hence, the solutions are $x=\frac{4}{5}$ and $x=\frac{1}{2}$.
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