I've been staring at this for 15mins plz help

29. explain the error a student found the product of 8 × 10 6 and 5 × 10 9 to be 4 × 10 15 . what is the error? what is the correct product?

Suppose a pendulum is l meters long. the time,t,in seconds that it tales to swing back and forth once is given by t=2.01

Graph y ≥ -x^2 - 1. click on the graph until the correct graph appears.