Motivation is a fire from within. If someone else tries to light that fire under you, chances are it will burn very briefly. – **Stephen R. Covey**

# Lecture - 4 Chapter 4 Quadratic Equations

00:00:40 Derivation for Quadratic formula

00:23:00 NCERT Exercise 4.3 Question 3 Find the roots of the following equations:

(i) x-\frac{1}{x}=-3, x \ne 0

(ii) \frac{1}{x+4}-\frac{1}{x-7}=\frac{11}{30}, x \ne -4, 7

00:32:00 NCERT Exercise 4.3 Question 4 The sum of the reciprocals of Rehman’s ages, (in years) 3 years ago and 5 years from now is 1/3. Find his present age.

00:36:50 NCERT Exercise 4.3 Question 5 In a class test, the sum of Shefali’s marks in Mathematics and English is 30. Had she got 2 marks more in Mathematics and 3 marks less in English, the product of their marks would have been 210. Find her marks in the two subjects.

00:43:10 NCERT Exercise 4.3 Question 6 The diagonal of a rectangular field is 60 metres more than the shorter side. If the longer side is 30 metres more than the shorter side, find the sides of the field.