With November almost over, how is your CBSE Class 12 Maths going on? In the last article we discussed Important Tips For Application of Integrals. You must have almost covered Application of Integration.

Let us take up the last topic of Calculus, i.e, **Differential Equation (Chapter 9), **which is a medium-sized chapter**. **Normally 5 marks are allotted to this chapter – one 1-mark question and one 4-mark question.

## Differential Equation

Your target time for first revision should be 4-5 hours appx for the six exercises (9.1 to 9.6 ) and the Misc exercise and also little bit of previous years’ questions from reference book.

**Some important questions from NCERT are as follows: **

Ex 9.1: |
Example 1(iii) | Question 5, 7, 12 |

Ex 9.2: |
Examples 3 | Questions 6, 8, 10 |

Ex 9.3: |
Examples 7 | Questions 1, 5, 7, 8, 10 |

Ex 9.4: |
Examples 12, 13 | Questions 4, 5, 10, 11, 13, 16, 18 |

Ex 9.5: |
Examples 16, 17 | Questions 6, 8, 9, 11, 15 |

Ex 9.6: |
Examples 19, 21 | Questions 3, 4, 7, 10, 14, 16, 19 |

Misc Ex 9 |
Examples 25, 26, 28 | Questions 1(ii), 2(ii), 5, 6, 8, 9, 13, 16 |

**Tips: **

- There are three methods of solving differential equations. But, normally, only one method works with one problem. You can quickly examine whether separation of variable is possible or not. If not, if the equation has (y/x) pattern, then it will be homogeneous. Otherwise, it will be linear differential equation
**.** - For Ex 9.3, some concepts of coordinate geometry are required (circle, ellipse etc). .

This first revision of this topic should be completed by 30th Nov. Better, if you can complete before that.

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