2.用x-1替换掉x得f(x)=(x-1)²+1=x²-2x+23.原式=lim(x→∞) (1-3/x)^[(-x/3)*(-3(x+2)/x)=e^(-3)4.y'|(1,0)=3x²-1|(1,0)=3×1²-1=2y-0=2(x-1)切线方程y=2x-25.y'=1/x,y'|x=e =1/e 切线: y-1=1/e(x-e)y=1/e*x6.y'=2cos2x,y"=-4sin2x7.y"=(cosx-sinx)'= -sinx-cosx