Question

11^2+12^2+13^2+ --+20^2​

Answer 1

Step-by-step explanation:

hope it helps u .........

Answer 2

Answer:

2485

Explanation

You know

$s_{n} = {1}^{2} + {2}^{2} + .... + {n}^{2} = \frac{n(n + 1)(2n + 1)}{6}$

Your sum is

$s = s_{20} - s_{10} \\ s = \frac{20 \times 21 \times 41}{6 } - \frac{10 \times 11 \times 21}{6} \\ s = \frac{10 \times 21}{6} (82 - 11) \\ s = 35 \times 71 = 2485$