Algebra 2 Common Core

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

Chapter 3 - Linear Systems - Mid-Chapter Quiz - Page 156: 11

Answer

The solution to this system of equations is $(-1, -2)$.

Work Step by Step

First, we rewrite the equations so that the variables are on one side while the constant is on the other: For the first equation, we subtract $8y$ from each side of the equation to shift all variables to one side of the equation: $10 = 6x - 8y$ Let us rewrite so variables are on the left and the constant is on the right: $6x - 8y = 10$ For the second equation, we just flip the $x$ and $y$ terms so that the $x$ term appears first in the equation: $-4x + 8y = -12$ We now can see that in the two equations, the $y$ terms are exactly the same except they have opposite signs. If we add these two equations together, we can eliminate the variable $y$ and just deal with one variable instead of two. Let us combine the two equations: $ 6x - 8y = 10$ $-4x + 8y = -12$ Let us add the two equations together to come up with a single equation: $2x = -2$ Divide each side by $2$ to solve for $x$: $x = -1$ 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: $8y + 10 = 6(-1)$ Multiply first, according to order of operations: $8y + 10 = -6$ Now, we subtract $10$ from both sides of the equation to isolate constants to the right side of the equation: $8y = -16$ Divide both sides by $8$ to solve for $y$: $y = -2$ The solution to this system of equations is $(-1, -2)$.
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