(1999•西安)化简x4+x2y2(x≤0)(  ) A.xx2+y2 B.-xx2+y2 C.x(x+y) D.-x(x+y)

问题描述:

(1999•西安)化简

x4+x2y2
(x≤0)(  )
A. x
x2+y2

B. -x
x2+y2

C. x(x+y)
D. -x(x+y)

∵x≤0

x4+x2y2
=
x2(x2+y2)
=-x
x2+y2

故选B.