十万火急，等数学高手救命！！！！

1.y′=[2x-cosx/(1-x)]′=2-[cosx/(1-x)]′=2-[(cosx)′(1-x)-cosx(1-x)′]/(1-x)^2=2+[sinx(1-x)+cosx]/(1-x)^2
y′(0)=2+(0+1)/1=3

2.y′=1/[x+√(x^2+1)]*[x+√(x^2+1)]′=[√(x^2+1)-x]*[1+1/2√(x^2+1)*2x]=[√(x^2+1)-x]*[1+x/√(x^2+1)]
y′(√3)=(2-√3)*(1+√3/2)=1/2

3.cos(x+y)+e^y=x
[cos(x+y)+e^y]′=x′
1=[cos(x+y)]′+(e^y)′=-sin(x+y)(x+y)′+e^y*y′=-sin(x+y)(1+y′)+e^y*y′=-sin(x+y)+[e^y-sin(x+y)]y′
y′=[1+sin(x+y)]/[e^y-sin(x+y)]
dy=[1+sin(x+y)]/[e^y-sin(x+y)]dx

y'=2+sinx/(1-x)*(-1/x),y'(0)=2