求下列函数的导数（1）y=（x+1）（x+2）（x+3）（2）y=2x^2+1/x-3/x^3（3）y=e^xcosx+sinx

求下列函数的导数：
(1) y=(x+1)(x+2)(x+3)
两边取对数得lny=ln(x+1)+ln(x+2)+ln(x+3)
两边对x取导数得y′/y=1/(x+1)+1/(x+2)+1/(x+3)，
故y′=y[1/(x+1)+1/(x+2)+1/(x+3)]=(x+1)(x+2)(x+3)[1/(x+1)+1/(x+2)+1/(x+3)]
=(x+2)(x+3)+(x+1)(x+3)+(x+1)(x+2)=3x²+12x+11
(2)y=2x²+(1/x)-(3/x^3)
y′=4x-(1/x²)+(9/x⁴)
(3)y=(e^x)cosx+sinx
y′=(e^x)cosx-(e^x)sinx+cosx=(e^x)(cosx+sinx)+cosx

（1）y'=(x+1)'(x+2)(x+3)+(x+1)(x+2)'(x+3)+(x+1)(x+2)(x+3)'=(x+2)(x+3)+(x+1)(x+3)+(x+1)(x+2)=3x²+12x+11（2）y'=(x²)'+(1/x)'+(-3/x^3)'=4x-1/x²+9/(x^4)（3）y'=(e^x)'cosx+(e^x)(cosx)'+(sinx...