Respuesta :
Answer: 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
[tex]x=\dfrac{43}{12}[/tex]
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.
