Pls help and really quick

If x+y+z=0 what is the value of [tex] {x}^{3} + {y}^{3} + {z}^{3} [/tex]

What is the point of inflection for the function f(x)=2cos4x on the interval (0, pi/2)

Consider a= {x|x is alive} f={x|x is in france} m={x|x is a national monument} w{x|x is a woman}. which statements are true regarding elements of the given sets? check all that apply.