Question

ДЗ по алгебре.
An=n²+3n+1
Найдите указаный член последовательности.
A9=9²+3×9+1=81+27+1=109
A20=
A50=
A71=

Answer 1

A20 =

$20^{2} + 3 \times 20 + 1 = 400 + 60 + 1 = 461$

A50 =

$50^{2} + 2 \times 50 + 1 = 2500 + 100 + 1 = 2601$

A71 =

$71^{2} + 2 \times 71 + 1 = 5041 + 142 + 1 = 5184$