那肯定是你算错了

没问题阿

What you wrote down in the third picture with question mark is correct. The book is also correct. But what you wrote down is the derivative of first order, which is zero. So there is no x term. If you compute further the derivative of second order, you will have x^2 term, which is the same as the book. Similar for third order and fourth order. They should be the same. Double check further.

，

The 4th floor is correct. You have made a mistake that it is the second-order term of Maclaurin series, so there is a factor (1/2!) you have missed multiplying by.

确定没错？？