Question

What is (a+b+c+d+...+n)^2
Who answers is a branliest

Answer 1

Answer:

(a+b+c+d+.....+n)^2

= a^2 + b^2 + c^2 + d^2 + ...... + n^2 + 2ab + 2ac + 2ad + .... + 2an + 2bc + 2bd +...... 2bn + 2cd + 2cn +...... and like terms

This can be easily seen or written down by binomial theorem , taking b+c+...+n as a' and then expanding by

(a+a')^2 = a^2 + a' ^2 + 2aa'

then again writing down a' = b+c+...+n

and so on.

Hope this helps you ! ｡◕‿◕｡