Question

what is the next term of the geometric sequence? -2.5, 5, -10, 20, ... a. -2.5 b. -40 c. 80 d. -2

Explanation:

Step1: Find common ratio $r$

$r = \frac{5}{-2.5} = -2$
Verify: $\frac{-10}{5}=-2$, $\frac{20}{-10}=-2$

Step2: Calculate next term

Multiply last term by $r$: $20 \times (-2)$

Answer:

b. -40