PLEASE HELP ME

What is the positive solution to the equation x² - 6x + 9 = 16?

Find the domain of the following expression: 1/(√x)-2

Find the commission on a $590.00 sale if the commission is 15%.

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 0 a. at what time does the particle reverse direction? b. when is the displacement positive? (round one decimal place and answer in interval notation) c. when is the displacement negative? (round one decimal place and answer in interval notation) d. when is the particle’s acceleration positive? (round one decimal place and answer in interval notation) e. when is the particle’s acceleration negative? (round one decimal place and answer in interval notation)