What is the absolute value or inequality of ∣x∣+8=15

Find an equation of the line perpendicular to the graph of 28x-7y=9 that passes through the point at (4,1)

Assume that there is a 11% rate of disk drive failure in a year. a. if all your computer data is stored on a hard disk drive with a copy stored on a second hard disk drive, what is the probability that during a year, you can avoid catastrophe with at least one working drive? b. if copies of all your computer data are stored on four independent hard disk drives, what is the probability that during a year, you can avoid catastrophe with at least one working drive?

Hello, i need compare km^2 and km. what's difference in this?