Which line has the mistake ?

What is the 9th term in the geometric sequence described by this explicit formula? an=-6. (2)(n-1) apex

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?

Select the correct answer and solve for y