Question

simplify: z^(k+1) - z^(k-1).
Ok, the result is (z^2-1)*z^(k-1), but I don't understand how you get it. Why is there z^2 and not z^(k^2)?

Answer 1

suppose you had \(z^7-z^5\) and you were asked to factor. what you would you get ?

Answer 2

(z^5*z^2) - (z^5*1)
z^5*(z^2 - 1)
but it doesnt feel right

Answer 3

but it is
so factor out z^(k-1)

Answer 4

z^(k-1)*(z^2-1)
hmm i was thinking too hard again. :S

Answer 5

thanks.

Answer 6

welcome :)