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6 solutions
Why don't you use formula for Sum of squares of first n natural numbers
The formula for sum of squares of n numbers will come in handy in this problem.
The formula is:
∑ n 2 = 6 ( n ) ( n + 1 ) ( 2 n + 1 )
It is easy to see that the sum of the squares of first four natural numbers is 3 0
Using the formula is overkill here!
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Though it is, the formula is a foolproof method. Any person with a little bit of common sense can use his skills to guess a number and use the hit and trial method. With the formula method, you can come up with the answer in a matter of seconds!
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No, it's really not needed here. Don't overcomplicate things. Here, knowing what the sigma operator means 'sum' is the important bit. It's much easier to add 1, 4, 9 and 16 than it is to put numbers into that formula (assuming you even know that formula - most people won't because sums of squares isn't exactly a common thing to need). This is a level 1 question after all...
ANSWER = n = 1 ∑ 4 n 2 = 1 2 + 2 2 + 3 2 + 4 2 = 1 + 4 + 9 + 1 6 = 3 0
1^2+2^2+3^2+4^2
1+2^2=5
3^2+4^2=5^2=25
5+25=30
6 ( 4 ) ( 5 ) ( 9 ) = 3 0
n = 1 ∑ 4 n 2 = 6 n ( n + 1 ) ( 2 n + 1 ) = 6 4 ( 5 ) ( 9 ) = 3 0
Remember to wrap math in \( ... \) or \[ ... \] to ensure proper formatting.
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Okay .Here after I'l follow it
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I have edited your latex. Please check if I did any change in your method. You may use this as a reference for later use. Click "Edit" to see latex.
Just a suggestion
1 2 + 2 2 + 3 2 + 4 2 = 3 0
1 + 4 + 9 + 1 6 = 3 0