the sum of 18 consecutive natural number is a perfect square the smallest possible value of this sum is
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45
Solution:
Let the number be
a, a + 1, a + 2, a + 3 _ _ _ _ _ _ a + 17.
This is an AP.
First term = a
Common difference, d = 1
Terms, n = 18
Sum of the terms
Substitute the values :
Sn = n/2 [ 2a + (n - 1)d ]
=> Sn = 18/2 [ 2a + 17 ]
=> Sn = 9 [ 2a + 17 ]
=> Sn = 18a + 153
For a = 1, Sn = 171
a = 2, Sn = 189
a = 3, Sn = 207
a = 4, Sn = 225
Here, 225 is the perfect square of 15.
Thus, 15 is a perfect square the smallest possible value of this sum is 225.
Let the number be
a, a + 1, a + 2, a + 3 _ _ _ _ _ _ a + 17.
This is an AP.
First term = a
Common difference, d = 1
Terms, n = 18
Sum of the terms
Substitute the values :
Sn = n/2 [ 2a + (n - 1)d ]
=> Sn = 18/2 [ 2a + 17 ]
=> Sn = 9 [ 2a + 17 ]
=> Sn = 18a + 153
For a = 1, Sn = 171
a = 2, Sn = 189
a = 3, Sn = 207
a = 4, Sn = 225
Here, 225 is the perfect square of 15.
Thus, 15 is a perfect square the smallest possible value of this sum is 225.
Answered by
5
Answer:
225...................................................................
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