X+3, -2x^(2)-6x, 4x^(3)+12x^(2) what is the 8th term in this geometric sequence

  a8 = -128x^8 -384x^7

Step-by-step explanation:

The formula for the general term of a geometric sequence with first term a1 and common ratio r is ...

  an = a1·r^(n-1)

Here, we have a1 = (x+3) and r = (-2x^2-6x)/(x+3) = -2x. Then the 8th term is ...

  a8 = (x+3)(-2x)^(8-1)

  a8 = -128x^8 -384x^7

hello from mrbilldoesmath!

answer:

a(n) - a(n-1) -3

discussion:

this ones a bit interesting. given a(n) = 5 - 3n consider this:

a(n-1) = 5 - 3(n-1)

          = (5 - 3n) + 3             => but a(n) = 5 - 3n, the first term

          = a(n)   + 3                 => subtract 3 from both sides

a(n-1) -3 = a(n)  

or

a(n) - a(n-1) -3

you,

mrb

use google you idiot omg you're so annoying

step-by-step explanation: