Respuesta :

Answer: -21, what ever number you have you subtract 3 from that number. So after -9 would be -12 and so on

Answer:

-729

Step-by-step explanation:

Given is a geometric sequence.

Therefore,

a = - 1, r = - 3 /(-1) = 3, n = 7

[tex] a_7 =? [/tex]

[tex] \because a_n = ar^{n-1} [/tex]

[tex] \therefore a_7 = (-1)(3)^{7-1} [/tex]

[tex] \therefore a_7 = (-1)(3)^{6} [/tex]

[tex] \therefore a_7 = (-1)(729) [/tex]

[tex] \therefore a_7 = -729 [/tex]