Question

find the sum of 11^3 + 12^3+......+25^3

Answer 1

Hey user !!

Here's the answer you are looking for

Please see the attachment for your answer.

ALTERNATIVE PROCESS (Using special series)

11³ + 12³ + .... + 25³

= (1³+2³+...+25³) - (1³+2³+...+10³)

We know,

1³ + 2³ + .... + n³

= ∑n³ = [n(n+1)/2]²

Here, we get

∑25³ - ∑10³

= [25(26)/2]² - [10(11)/2]²

After calculating (as shown in the attachment), answer will be 102600.


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