Alternative method used when denominator limit is not zero. First, study the denominator limit, which is used when the denominator limit is a non-zero constant.

2.

When the denominator limit is zero and the molecular limit is a constant not equal to zero, the reciprocal method is used.

3.

When the denominator limit is zero and the molecular limit is zero, the method of zero elimination factor (factorization) can be used.

4.

The method of eliminating zero factor (physicalization) has zero denominator limit and zero molecular limit, which cannot be decomposed, but can be used in physicalization. Square difference, cubic difference, cubic sum can all be used for physicalization.

5.

Zero factor substitution method. Use the first important restriction: lim [x->; 0]sinx/x= 1, denominator limit is zero, and molecular limit is zero, which cannot be decomposed or materialized, but it is used when it appears or can be converted into sinx/x, and trigonometric function formulas are often used together.

6.

Infinite transformation method, used when denominator and numerator are infinite, often borrows the properties of infinity and infinitesimal.