Which is the correct way to write the square root of 16

I’m stuck on this i don’t understand.

Find the magnitude of the torque about p if an f = 80-lb force is applied as shown. (round your answer to the nearest whole number.) ft-lb

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)