Question

qual é o sexto termo da P.G (-240,-120,-60,...) ?

Answer 1

    a6 = - 240. (1/2)^5

    a6 = - 240 .1
                      32
    a6 = - 240: 16
                32 : 16

     a6 = -  15
                  2

Answer 2

$a_{1} = - 240$
$a_{2} = - 120$

$q = \frac{a_{2}}{a_{1}} = \frac{- 120}{- 240} = \frac{1}{2}$

$a_{n} = a_{1} * q^{n - 1}$
$a_{6} = a_{1} * q^{6 - 1}$
$a_{6} = a_{1} * q^{5}$

$a_{6} = (- 240) * ( \frac{1}{2})^{5}$

$a_{6} = (- 240) * \frac{1^{5}}{2^{5}}$

$a_{6} = (- 240) * \frac{1}{32}$

$a_{6} = \frac{- 240}{32}$

$a_{6} = \frac{- 15}{2}$