Question

下列各式运用平方差公式分解因式正确的是

1. A.
   x²+y²＝(x+y)(x+y)
2. B.
   x²-y²＝(x+y)(x-y)
3. C.
   -x²+y²＝(-x+y)(-x-y)
4. D.
   -x²-y²＝-(x+y)(x-y)

Answer 1

B