Can you please help explain this problem?

Maurice says that a(square)+ b(square)=(a+b)(a+b). Is this always true, never true, or sometimes true?

Explain.

It is true whenever a=0 or b=0 or both=0, because

(a+b)²=a²+2ab+b²
So when either or both of a and b is zero, the equality is true because the 2ab term disappears.