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NCERT Exemplar Solutions Class 10 Mathematics Solutions for Quadratic Equations - Exercise 4.4 in Chapter 4 - Quadratic Equations

Question 4 Quadratic Equations - Exercise 4.4

A natural number, when increased by 12, equals 160 times its reciprocal. Find the number.

Answer:

Let the natural number = x

When the number increased by 12 = x + 12

Reciprocal of the number = 1/x

According to the question, we have,

x + 12 = 160 times of reciprocal of x

x + 12 = 160/ x

x( x + 12 ) = 160

x2 + 12x – 160 = 0

x2 + 20x – 8x – 160 = 0

x( x + 20) – 8( x + 20)= 0

(x + 20) (x – 8) = 0

x + 20 = 0 or x – 8 = 0

x = – 20 or x = 8

Since, natural numbers cannot be negative.

The required number = x = 8

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