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: 12

Answer

The solution to this system of equations is $(\frac{5}{2}, 2)$.

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 $11$ from each side of the equation to shift constants to one side of the equation: $-2c = 3d - 11$ Subtract $3d$ from both sides of the equation to move all variables to the left side of the equation: $-2c - 3d = -11$ We now can see that in the two equations, the $c$ terms are exactly the same except they have opposite signs. If we add these two equations together, we can eliminate the variable $c$ and just deal with one variable instead of two. Let us combine the two equations: $-2c - 3d = -11$ $ 2c - 7d = -9$ Let us add the two equations together to come up with a single equation: $-10d = -20$ Divide each side by $-10$ to solve for $d$: $d = 2$ Now that we have the value for $d$, we can plug it into one of the equations to solve for $c$. Let us plug in the value for $d$ into the first equation: $11 - 2c = 3(2)$ $11 - 2c = 6$ Now, we subtract $11$ from both sides of the equation to isolate constants to the right side of the equation: $- 2c = -5$ Divide both sides by $-2$ to solve for $c$: $c = \frac{5}{2}$ The solution to this system of equations is $(\frac{5}{2}, 2)$.
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