Find two consecutive odd positive integers, sum of whose squares is 290.
Answers
Answer:
11 and 13
Step-by-step explanation:
Let a be the first of the two odd integers. The next odd integer is then a+2.
The sum of their squares = 290
=> a² + (a+2)² = 290
=> a² + a² + 4a + 4 = 290
=> 2a² + 4a + 4 = 290
=> a² + 2a + 2 = 145
=> (a+1)² + 1 = 145
=> (a+1)² = 144
=> a+1 = ±12
=> a = ±12-1
Since we are told that a is positive, it must be
a = 12-1 = 11
and
a+2 = 13
Sol-
Let the first no. be x and the 2nd be (x+2)
According to the given condition,
x^2 + (x+2)^2 = 290
x^2 + x^2 + 4x + 4 = 290
2 x^2 + 4x +4 - 290 = 0
2x^2 +4x - 286 =0
x^2 + 2x - 143 = 0 (Dividing by 2)
x^2 + 13x -11x -143 =0
x (x +13) - 11 (x +13) = 0
(x -11) (x +13) =0
x -11=0 or x + 13 =0
x= 11 or x = -13
But x is a positive integer
x = 11
and x + 2 = 11+2 = 13
Thus, the two nos. are 11 and 13.
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