The difference of squares of two consecutive natural numbers is 2011. Find the numbers.
152 a perfect square? Explain.
2.
3.
Find the Pythagorean triplet whose smallest number is 20.
Answers
(x+1)²-x²=2011
x²+2x+1-x²=2011
2x+1=2011
2x=2010
x=1005
and the other no.is 1006
the pythagoras triplets 20²+21²+22²=400+441+484=1325
Solution :-
(1)
Let us assume that, smaller number is x .
So,
→ Greater number = (x + 1)
then,
→ (x + 1)² - x² = 2011
→ (x² + 1 + 2x) - x² = 2011
→ x² - x² + 1 + 2x = 2011
→ 2x = 2011 - 1
→ 2x = 2010
→ x = 1005
therefore,
→ Smaller number = 1005
→ Greater number = 1005 + 1 = 1006 .
Hence, required two consecutive natural numbers are 1005 and 1006 .
(2)
We know that,
- A perfect square number unit digit is 0, 1, 4, 5, 6 and 9 only .
So,
→ 152 = unit digit 2 .
Therefore, 152 is not a perfect square number .
(3)
We know that
- For all natural number n > 2 , (2n , n² - 1 and n² + 1) is a pythagorean triplet .
So,
→ Smallest number = 2n
→ 2n = 20
→ n = 10
then,
→ n² - 1 = 10² - 1 = 100
→ n² + 1 = 10² + 1 = 101
therefore, the pythagorean triplet whose smallest number is 20 :- 20, 99 and 101 .
Learn more :-
let a and b positive integers such that 90 less than a+b less than 99 and 0.9 less than a/b less than 0.91. Find ab/46
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