Question

find the square numbers formed by adding two consecutive natural numbers lying between 20 and 40 ?​

Answer 1

You should use the formula from eleventh class mathematics given in unit sequence and series. Sum of square of number like this is given by n(n+1)(2n+1) divided by 6. You have to first calculate for n=100 and then for n=20. After that subtract second value from first ,i. e. Obtain from n=100. I hope u will get my point and correct answer too