square
Level
pending
what is the sum of 2x2+3x3+4x4+5x5+6x6+7x7+8x8+9x9+10x10=
The answer is 384.
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1 solution
consider the sequence
1 =1
1 + 3 = 2x2
1 + 3 + 5 = 3x 3
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thus we can see that the sum of first n odd numbers is the square of the number of numbers we have taken
therefore
2x2 = 1+3
3x3 = 1+ 3+5
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10x10 = 1 + 3 +5 ..........
thus substitute the value