Question

ache a soma eral dos 10 primeiros termos da pg (-1,4,-16,...)

Answer 1

a1=-1
q=a2/a1= 4/-1=-4
n=10

fórmula do soma da pg:
$S_{n}= \frac{a_{1}.( q^{n}-1 ) }{q-1}$
$S_{n}=\frac{-1.( -4^{10}-1 )}{-4-1}$
$S_{n}= \frac{-1.(1048576 -1)}{-5}$
$S_{n}= \frac{-1.(1048575)}{-5}$
$S_{n}= \frac{-1048575}{-5}$
$S_{n}= 209715$