Check all that are true about the polynomial function f(x)=x^4-x^2 B. f(x) has a relative maximum of (0,0)

C. f(x) has a double root at x=1

D.(x+1) is a factor of f(x)

F. f(x) is decreasing when x<-1

E. f(x) has a range of [-3,♾)