CPM Homework Help : A2C Problem 11-21

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Home > A2C > Chapter 11 > Lesson 11.1.2 > Problem 11-21

11-21.

Solve each system of equations below.

$\left. \begin{array} { l } { x - 2 y = 7 } \\ { 2 x + y = 3 } \end{array} \right.$
Answer (a):
$\left(\frac{13}{15}, -\frac{11}{5}\right)$

$\left. \begin{array} { r } { \frac { x + 4 y } { 3 } - \frac { 6 y - x } { 4 } = - 3 } \\ { \frac { x } { 10 } + 5 y = 2 } \end{array} \right.$
Step 1(b):
$4x + 16y − 18y + 3x = −36$
$x + 50y = 20$
Step 2(b):
$7x − 2y = −36$
$x = 20 − 50y$
Step 3(b):
$7\left(20 − 50y\right) − 2y = −36$
Step 4(b):
$y =\frac{1}{2}$
Step 5(b):
$\frac{x}{10}+5\left(\frac{1}{2}\right)=2$
Answer (b):
$x = −5$
$\left(-5, \frac{1}{2}\right)$

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