e^x(1+Bx+Cx^2)-1=Ax+ο(x^2),
e^x(1+Bx+Cx^2)=1+Ax+ο(x^2),
x->0时
[e^x(1+Bx+Cx^2)-1]/x=A+ο(x),
x->0时对上式用罗必塔法则求极限
limx->0[e^x(1+Bx+Cx^2)+e^x(B+2Cx)]=A
limx->0[e^x(B+1)+e^x(Bx+Cx^2+2Cx)]=A
所以B+1=A,C为任何数
taylor展开算了......
e^x = 1 + x + x^2 / 2 + x^3 / 3! + ......
(1 + x + x^2 / 2 + o(x^2))(1+Bx+Cx^2)=1+Ax+o(x^2)
((1+Bx+Cx^2) + (x+Bx^2+o(x^2)) + (x^2 / 2 + o(x^2)) + o(x^2))=1+Ax+o(x^2)
1 + (1+B)x+(C+B+1/2)x^2 + o(x^2) = 1 + Ax + o(x^2)
1 + (1+B)x+(C+B+1/2)x^2 + o(x^2) = 1 + Ax + o(x^2)
= = 我忘了o(x^2)包不包括x^2了......
= = 好吧根据楼上的, 不包括
A=1+B.
问老师最快了1