Algebra 2 Common Core

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

Chapter 3 - Linear Systems - 3-3 Systems of Inequalities - Practice and Problem-Solving Exercises - Page 155: 68

Answer

The solution to this system of equations is $\left(-\dfrac{4}{7}, \dfrac{1}{14}\right)$.

Work Step by Step

First, we rewrite the equations so that the variables are on one side while the constant is on the other: $-3x + 4y = 2$ $ 5x - 2y =-3$ We see that if we multiply the second equation by $2$, then the $y$ terms will have opposite numerical coefficients. If we add these two equations together, we can eliminate the variable $y$ and just deal with one variable instead of two. Let us multiply the second equation by $2$ to obtain the equivalent system: $-3x + 4y = 2$ $10x - 4y = -6$ Add the two equations together to come up with one single equation: $(-3x+4y)+(10x-4y)=2+(-6)\\ 7x = -4$ Divide each side by $7$ to solve for $x$: $x = -\dfrac{4}{7}$ Now that we have the value for $x$, we can plug it into one of the equations to solve for $y$. Let us plug in the value for $x$ into the first equation: $2-4y-3x\\ 2 = 4y - 3\left(-\frac{4}{7}\right)$ $2 = 4y + \frac{12}{7}$ Subtract $\dfrac{12}{7}$ from both sides of the equation to isolate constants to the right side of the equation: $2 - \dfrac{12}{7}=4y$ Convert $2$ into a fraction with $7$ as its denominator: $\dfrac{14}{7} - \dfrac{12}{7}=4y$ $ \dfrac{2}{7}=4y$ Multiply $\dfrac{1}{4}$ to both sides of the equation: $ \dfrac{1}{4} \cdot \dfrac{2}{7}=\dfrac{1}{4} \cdot 4y\\ \dfrac{2}{28}=y$ Divide both numerator and denominator by $2$ to simplify the fraction: $\dfrac{1}{14}=y$ The solution to this system of equations is $\left(-\dfrac{4}{7}, \dfrac{1}{14}\right)$.
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