Find two consecutive positive integers, sum of whose squares is 365.m.
Answers
Let us say, the two consecutive positive integers be x and x + 1.
Therefore, as per the given statement,
x2 + (x + 1)2 = 365
⇒ x2 + x2 + 1 + 2x = 365
⇒ 2x2 + 2x – 364 = 0
⇒ x2 + x – 182 = 0
⇒ x2 + 14x – 13x – 182 = 0
⇒ x(x + 14) -13(x + 14) = 0
⇒ (x + 14)(x – 13) = 0
Thus, either, x + 14 = 0 or x – 13 = 0,
⇒ x = – 14 or x = 13
since, the integers are positive, so x can be 13, only.
So, x + 1 = 13 + 1 = 14
Therefore, the two consecutive positive integers will be 13 and 14.
Let the consecutive positive integer be
x and ( x + 1 )
Sum of the square of the number is = 365
x² + ( x + 1 )2 = 365
x² + x² + 2x + 1 = 365
2x² + 2x + 1 = 365
2x² + 2x + 1 - 365 = 0
2x² + 2x - 364 = 0
Divide LHS and RHS by 2
2x² / 2 + 2x / 2 - 364 / 2 = 0 / 2
x² + x - 182 = 0
x² + 14x - 13x - 182 = 0
x ( x + 14 ) - 13 ( x + 14 ) = 0
( x + 14 ) ( x - 13 ) = 0
if x + 14 = 0 and x - 13 = 0
So
x = -14 ( minus neglected )
x = 13
So : x = 13
other number = x + 1 = 13 + 1 = 14