What is formula for following geometric sequence -5,-10,-20,-40

x = -5 * (2)^(n-1)

Step-by-step explanation:

If we look a the supplied n elements of the sequence, and we divide each of them by -5.

1 = -5, -5/-5 = 1

2 = -10, -10/-5 = 2

3 = -20, -20/-5 = 4

4 = -40, -40/-5 = 8

We realize that we have all the powers of 2 there.

So the formula will start with -5 (the first element), then multiplied by a power of 2.

We can verify for the 4th element, where n = 4:

i'm assuming it's looking for the missing length, which should be 4cm

hope this !

t = 3

step-by-step explanation:

put t = 3 in this expression :

(3²-1)(3²-2)(3² - 3)(3² - 4) = 8×7×6×5 = 56×30 = 1680