When x approaches 0, firstly, the cube root number (1+x square)-1 equals one-third x square, and the root number (1+sinx)- 1 equals one-half sinx{ Use (1+x). If you don't understand the topic, please see the Taylor formula section at the back. You should not understand it. Anyway, what you need to remember now is that when x approaches 0 (1+x), the power sum of a 1+ax is equivalent. Sinx is the equivalent infinitesimal of x, and the denominator becomes one sixth of the cube of X.

(The subject may not have read this paragraph, but I can't help saying that it can be written by mclaughlin formula: sinx = the cubic of x-x+o (the cubic of x), tanx = the cubic of x+x+o (the cubic of x), and then the above sinx-tanx becomes the cubic of negative half x).

The third power of negative one-half x is above, and the third power of one-sixth x is below, which is -3.

Don't worry, now you just need to remember some equivalent infinitesimals, such as the power of a, the equivalence of 1+x 0+AX when x approaches 0, and the rest you can understand by studying Taylor formula.

Pure hand tour, seeking adoption.