### Home > CCA > Chapter 4 > Lesson 4.2.4 > Problem4-71

4-71.

Solve these systems of equations using any method. Check each solution, if possible. Homework Help ✎

1. $2 x + 3 y = 9 \\ - 3 x + 3 y = - 6$

• One strategy to solve this system of equations is to multiply the bottom equation by −1 so you can eliminate.

2x + 3y = 9
3x − 3y = 6
5x = 15

After finding x, plug in its value into one of the equations to find the value of y.

x = 3
y = 1

1. $x=8−2y\\y−x=4$

• Because one of the equations above is already solved for x, one strategy to solve this system is to substitute the first equation in for x in the second equation.

1. $y = - \frac { 1 } { 2 } x + 7 \\ y = x - 8$

• Use the Equal Values Method.

1. $9 x + 10 y = 14 \\ 7 x + 5 y = - 3$

• Refer to part (a).

x = −4; y = 5