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Three Consecutive Natural Numbers Are Such that the Square of the Middle Number Exceeds the Difference of the Squares of the Other Two by 60. Assume the Middle Number to Be X and Form a - ICSE Class 10 - Mathematics

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Question

Three consecutive natural numbers are such that the square of the middle number exceeds the difference of the squares of the other two by 60.
Assume the middle number to be x and form a quadratic equation satisfying the above statement. Hence; find the three numbers.

Solution

Let the numbers be x – 1, x and x + 1.
From the given information,
x2 = (x + 1)2 – (x – 1)2 + 60
x2 = x2 + 1 + 2x – x2 – 1 + 2x + 60
x2 = 4x + 60
x2 – 4x – 60 = 0
(x – 10) (x + 6) = 0
x = 10, -6
Since, x is a natural number, so x = 10.
Thus, the three numbers are 9, 10 and 11.

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APPEARS IN

 Selina Solution for Selina ICSE Concise Mathematics for Class 10 (2018-2019) (2017 to Current)
Chapter 6: Solving (simple) Problems (Based on Quadratic Equations)
Ex.6A | Q: 13
Solution Three Consecutive Natural Numbers Are Such that the Square of the Middle Number Exceeds the Difference of the Squares of the Other Two by 60. Assume the Middle Number to Be X and Form a Concept: Quadratic Equations.
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