Suppose a classmate claims that the differnece between (x+2)2 and (x2+4) mist be 0. is your classmate correct? choose the best explanation.

The two are not the same, even if you set x = -2, the second becomes 8, not 0 (your option B is in error as it did not square the negative as it should have). 

If you subtract one from the other, you get: 

(x + 2)² - (x² + 4) 
(x² + 4x + 4) - x² - 4 
4x