Is the time it takes for a light bulb to burn outtime it takes for a light bulb to burn out a discrete random variable, a continuous random variable, or not a random variable?

Can someone answer these problems for me

Which of the expressions (on the photo document i inserted) together represent all solutions to the following equation? 8cos(12x)+4=-4 *the answer should be in degrees.* > i would like for someone to explain the process to find the solutions for this.

Aclassmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.