An equation in the system is y = x + 1. What is the other equation in the system if the solution is only at (0, 1) ?

x - y = 1

2x + 2y = 4

x + y = 1

x + 2y = 2

A)

x - y = 1

0 - 1 = 1

-1 = 1

Not true.

B)

2x + 2y = 4

2 (0) + 2 (1) = 4

0 + 2 = 4

2 = 4

Not true

C)

x + y = 1

0 + 1 = 1

1 = 1

True

D)

x + 2y = 2

0 + 2 (1) = 2

2 = 2

True

The answer is C and D.