Question

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

Answer 1

The formula/rule for this sequence is 2x (x times 2).

The first thing you'd have to do is figure out how much the terms are going up each time. Each time the terms are going up by twice the amount before. Since the 10 or the 40 aren't positive numbers, the numbers are hoing up by 2 instead on -2.

I hope this helps!