Carlos solved the system of equations below. What mistake did he make in his work?

2x + y = 5
x − 2y = 10

y = 5 − 2x
x − 2(5 − 2x) = 10
x + 10 + 4x = 10
5x + 10 = 10
5x = 0
x = 0

2(0) + y = 5
y = 5

He should have substituted 5 + 2x

He did not distribute correctly

He combined like terms incorrectly, it should have been 4x instead of 5x

He made no mistake

Question

Carlos solved the system of equations below. What mistake did he make in his work?

2x + y = 5
x − 2y = 10

y = 5 − 2x
x − 2(5 − 2x) = 10
x + 10 + 4x = 10
5x + 10 = 10
5x = 0
x = 0

2(0) + y = 5
y = 5

 He should have substituted 5 + 2x

 He did not distribute correctly

 He combined like terms incorrectly, it should have been 4x instead of 5x

 He made no mistake

goformit100 · Answer

He combined like terms incorrectly, it should have been 4x instead of 5x