Is -root 16 a rational number

Part a: sam rented a boat at $225 for 2 days. if he rents the same boat for 5 days, he has to pay a total rent of $480. write an equation in the standard form to represent the total rent (y) that sam has to pay for renting the boat for x days. (4 points)

In which direction does the left side of the graph of this function point? f(x) = 3x3 - x2 + 4x - 2

Idon't get undoing if its pass adding and subtracting so can someone ? x-2 over 5 = 18