计算√（a+1）²-（√a-1）²=（ ）A.2B.-2C.2aD.-2a

计算√（a+1）²-（√a-1）²=（ ）A.2B.-2C.2aD.-2a
计算√（a+1）²-（√a-1）²=（ ）
A.2
B.-2
C.2a
D.-2a

计算√（a+1）²-（√a-1）²=（ ）A.2B.-2C.2aD.-2a
因为根号里面的数要大于等于0,由√a-1可得：a-1≥0,a≥1.
所以：
√（a+1）²-（√a-1）²
=a+1-(a-1)
=a+1-a+1
=2
选A