PLEASE HELP ME I ONLY HAVE 20 MINUTES The height of a tennis ball
tossed into the air is modeled by h(x) = 40x -16x^2, where x is elapsed time in seconds. During what time interval will the tennis ball be at least 15 feet above the ground?

I’m pretty sure it’s D but I need an explanation why!!!

Suppose there is a simple index of three stocks, stock abc, stock xyz, and stock qrs. stock abc opens on day 1 with 4000 shares at $3.15 per share. stock xyz opens on day 1 with 5000 shares at $4.30 per share. stock qrs opens on day 1 with 6000 shares at $4.60 per share. the price of stock abc on day 8 begins at $3.50. the price of stock xyz on day 8 begins at $3.90. stock qrs opens on day 8 with a price of $4.50 per share. assume that each stock has the same number of shares that it opened with on day 1. what is the rate of change of this simple index over 1 week?

Simplify (1/2)4th power a. (1/16) b.(1/8) c.(1/4)

The graph of f(x) = |x| is transformed to g(x) = |x + 11| - 7. on which interval is the function decreasing?