Question

Write an expression for the general or nth term, an, for the geometric sequence. 1, -4, 16, -64, . . .

Answer 1

\[A _{n}=ar^{n-1}\]
a is the first term.
r is the common ratio.

Answer 2

you can find a and r easily. Once you do that, just sub them into that expression. And you're done.

Answer 3

Thanks Azteck but I don't understand, can you explain a little more please

Answer 4

Basically, he's saying see how you go from the first term to the second term. For this question, you can easily spot it without using a formula. Since its a geometric sequence, you multiply the first term with a number to get the second term. Want to make it easy? Divide the second term by the first term.

Answer 5

thanks Hsrikako