Math question need help with substation please?

Use the discriminant to describe the roots of each equation. then select the best description. 2m2 + 3 = m double root real and rational roots real and irrational roots non-real roots

Express the following as a function of a single angle. cos(60) cos(-20) - sin(60) sin(-20)

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 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)