The sum of $15^{2} + 16^{2} + 17^{2} + ... + 30^{2}$ is equal to

Question

Dr. Abubacker · Accepted Answer

(b)
$15^{2} + 16^{2} + 17^{2} + ... + 30^{2}$
$= 1^{2} + 2^{2} + ... + 30^{2} - (1^{2} + 2^{2} + ... + 14^{2})$
$= \frac{30(31)(61)}{6} - \frac{14(15)(29)}{6}$
$= \frac{56730 - 6090}{6} = 8440$

Q. The sum of $15^{2} + 16^{2} + 17^{2} + ... + 30^{2}$ is equal to

Explanation

Reviewed by Dr. Abubacker

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