高数求导 我怎么感觉答案给的不对?少个2乘根号下x加根号x?

2025-05-11 02:42:42
推荐回答(2个)
回答1:

嗯,对,是少了那项
y'=1/2*[x+√(x+√x)]^(-1/2)*[1+1/(2*√(x+√x))(1+1/2√x)]
=1/2*[x+√(x+√x)]^(-1/2)*[(1+2√(x+√x)]/2*√(x+√x)*(1+2√x)/2√x
=1/8* 1/[√x*√(x+√x)*(x+√(x+√x))] *[1+2√x+2√(x+√x)+4√x*√(x+√x)]

回答2:

我帮你做一遍
y^2=x+√(x+√x)
y^2-x=√(x+√x)
y^4-2xy^2+x^2=x+√x
等式两边对x求导
4y^3*y'-2y^2-4xy*y'+2x=1+1/2√x
(4y^3-4xy)*y'=2y^2-2x+1+1/2√x
y'=(4√x*y^2-4x√x+2√x+1)/(8√x*y^3-8xy√x)
={4√x*[x+√(x+√x)]-4x√x+2√x+1}/{8√x*y*(y^2-x)
=[1+2√x+4√x*√(x+√x)]/{8√x*√[x+√(x+√x)]*√(x+√x)}
所以你给出的答案是正确的