Three consecutive positive integers are raised to the
first, second and third powers respectively and then
added. The sum so obtained is a perfect square, whose
square root equals the total of the three original inte-
gers. Which of the following best describes the mini-
mum, say m, of these three integers?
(a) 1 <= m <= 3
(b) 4 <= m < = 6
(c) 7 <= m <= 9
(d) 10 <= m <= 12
(e) 13 <= m <= 15
Answers
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Answer:
Let the three integers be m−1,m,m+1
As given,
m−1+m
2
+(m+1)
3
=(m−1+m+m+1)
2
m−1+m
2
+m
3
+1+3m
2
+3m=9m
2
m
3
−5m
2
+4m=0
m(m
2
−5m+4)=0
m(m−1)(m−4)=0
m=0,1,4
m cannot be 0 o 1 else the smallest number will be either -1 or 0 which is not possible.
Hence, m=4
and smallest number then is 3
Thus correct answer is 1≤m≤3
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