Question

Dallas solved the system of equations below. What mistake did he make in his work?
3x + y = 6
x − 2y = 2

y = 6 − 3x
x − 2(6 − 3x) = 2
x − 12 + 6x = 2
5x − 12 = 2
+12 +12
5 x over 5 equals 14 over 5
x = 2.8

3(2.8) + y = 6
8.4 + y = 6
−8.4 −8.4
y = −2.4

a. He should have substituted 6 + 3x.
b. He combined like terms incorrectly. It should have been 7x instead of 5x.
c. He made a mistake in distributing −2.
d. He made no mistake.

Answer 1

@iGreen

Answer 2

B..should've added x + 6x = 7x. I think he subtracted instead and got 5x.

Answer 3

ok thanks!