幂函数的求导公式: (x^n)'=n*x^(n-1)
y=√x=x^(1/2)
y'=1/2* x^(1/2-1)
=1/2*x^(-1/2)
=1/2* 1/x^(1/2)
=1/2*1/√x
=1/(2√x)
不懂追问