2. Reciprocal method, which is used when the denominator limit is zero and the molecular limit is not zero. The reciprocal limit must be zero, which is infinite in itself.
3. Zero-factor rounding method, the numerator limit of denominator is all 0, which is a polynomial.
4. Physicochemical method, the denominator molecular limit is all 0, and it is used when it is free radical.
5. Use the properties of infinitesimal and infinitesimal.
6. Use two important restrictions.
7. Equivalent infinitesimal replacement.
8. Robita rule, used for amorphous.
9. Use Taylor formula.
10. Using the pinch theorem.
Every time you learn a math difficulty, try to explain it to others and make him understand. Only when you can explain it clearly can you really unde