Question

s=1.2+2.3+3.4+............... ..+n(n+1)=20 terminos

Answer 1

Respuesta:

s = 3080

Explicación paso a paso:

S = 1.2+2.3+3.4+............... ..+n(n+1) -->20 Términos

$s = \overset{20}{ \underset{n= 1}{\sum}}n(n + 1)$

$s = \overset{20}{ \underset{n= 1}{\sum}} \: n^{2} + n$

$s = \overset{20}{ \underset{n= 1}{\sum}} \: n^{2} \: \: + \: \:\overset{20}{ \underset{n= 1}{\sum}} n$

$s = \frac{20(20 + 1)(40 + 1)}{6} \: \: + \: \frac{20(20 + 1)}{2}$

$s = 2870\: \: + \: 210$

$s = 3080$