Probability density functions

Hi could I please get some urgent help with the following?

1) Let X be a continuous random variable with probability density function given by:

fX(x) = 2x^(−3) for x>=1

_______0 otherwise

(a) Show that fX(x) is a valid density function.

(b) Explain why fX(1) = 2 is an acceptable value for the density function when probabilities must be less than 1.

(c) Find the distribution function for X.

(f) Solve the equation FX(x) = 0.5 for x. What importance does this value have?