# NCERT Solutions for Class 10 Maths Chapter 4 : Quadratic Equations 70

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## Chapter 4 : Quadratic Equations 70

### 4.1 Introduction

When we equate this polynomial to zero, we get a quadratic equation. Quadratic equations come up when we deal with many real-life situations. For instance, suppose a charity trust decides to build a prayer hall having a carpet area of 300 square metres with its length one metre more than twice its breadth. What should be the length and breadth of the hall? Suppose the breadth of the hall is x metres. Then, its length should be (2x + 1) metres.

Quadratic equations arise in several situations in the world around us and in different fields of mathematics. Let us consider a few examples.
Example 1 : Represent the following situations mathematically:
(1) John and Jivanti together have 45 marbles. Both of them lost 5 marbles each, and the product of the number of marbles they now have is 124. We would like to find out how many marbles they had to start with.

### 4.3 Solution Of A Quadratic Equation By Factorisation

You have observed, in Chapter 2, that a quadratic polynomial can have at most two zeroes. So, any quadratic equation can have atmost two roots. You have learnt in Class IX, how to factorise quadratic polynomials by splitting their middle terms. We shall use this knowledge for finding the roots of a quadratic equation. Let us see how.

### 4.4 Solution Of A Quadratic Equation By Completing The Square

In the previous section, you have learnt one method of obtaining the roots of a quadratic equation. In this section, we shall study another method. Consider the following situation:
The product of Sunita’s age (in years) two years ago and her age four years from now is one more than twice her present age. What is her present age?

### 4.5 Nature Of Roots

A pole has to be erected at a point on the boundary of a circular park of diameter 13 metres in such a way that the differences of its distances from two diametrically opposite fixed gates A and B on the boundary is 7 metres. Is it possible to do so? If yes, at what distances from the two gates should the pole be erected?

### 4.6 Summary

In this chapter, you have studied the following points:
1. A quadratic equation can also be solved by the method of completing the square.