Which equations illustrate the commutative property of multiplication?
choose exactly two answers that are correct.
a.
-1/2 • 3.4 = 3.4 • (-1/2)
b.
–8 • (5 + 3.1) = (5 + 3.1) • (–8)
c.
–4 • (5 + 7.1) = –4 • 5 + (–4) • 7.1
d.
–8 • (4 • 1) = (–8 • 4) • 1

In one day there are too high tides into low tides and equally spaced intervals the high tide is observed to be 6 feet above the average sea level after six hours passed a low tide occurs at 6 feet below the average sea level in this task you will model this occurrence using a trigonometric function by using x as a measurement of time assume the first high tide occurs at x=0. a. what are the independent and dependent variables? b. determine these key features of the function that models the tide: 1.amplitude 2.period 3.frequency 4.midline 5.vertical shift 6.phase shift c. create a trigonometric function that models the ocean tide for a period of 12 hours. d.what is the height of the tide after 93 hours?