1. Which of the following ordered pairs are solutions to the system of equations below? 4x + 4y = -9
Y = 2x - 13
A : (-3, -7)
B : (3-7)
C : (3,7)
D : (-3,7)

 B: (3, -7)

Step-by-step explanation:

4x + 4y = -9

         y = 2x - 13

Use Substitution:

4x + 4(2x - 13) = -9

4x + 8x - 52 = -9

       12x - 52 = -9

               12x = 43

None of the options provided are valid so either there is a typo on your worksheet or you typed in one of the equations wrong.

Plan B: Input the choices into the equation to see which one makes a true statement.

               4x + 4y = -9

A) (x, y) = (-3, -7)

               4(-3) + 4(-7) = -9

                -12   +   -28 = -9

                             -40 ≠ -9

B) (x, y) = (3, -7)

               4(3) + 4(-7) = -9

                12   +   -28 = -9

                             -16 ≠ -9

C) (x, y) = (3, 7)

               4(3) + 4(7) = -9

                12   +   28 = -9

                            40 ≠ -9

D) (x, y) = (-3, 7)

               4(-3) + 4(7) = -9

                -12   +   28 = -9

                              16 ≠ -9

Obviously there is something wrong with the first equation because none of the options provide a true statement.

               y = 2x - 13

A) (x, y) = (-3, -7)

               -7 = 2(-3) - 13

               -7  = -6    -13

                -7 ≠ -19

B) (x, y) = (3, -7)

               -7 = 2(3) - 13

               -7  = 6    -13

                -7 = -7                   this works!!!

C) (x, y) = (3, 7)

               7 = 2(3) - 13

               7  = 6    -13

                7 ≠ -7

D) (x, y) = (-3, 7)

               7 = 2(-3) - 13

               7  = -6    -13

                7 ≠ -19

Option B is the only one that provides a true statement so this must be the answer.