问题 填空题
化简
x4+x2y2
=______.
答案

根据题意得,

①当x≥0时,

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

②当x<0时,

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

故答案为x

x2+y2
或-x
x2+y2

选择题
单项选择题