Question

Use Descartes' Rule of Signs to determine the possible number of positive real zeros and the possible number of negative real zeros for the function.
F(x)=7x^5-8x^4+8x^3-5

Answer 1

there are +-+- thre changes of sign hence three positive real zeros.
put x=-x
F(x)=-7x^5-8x^4-8x^3-5
you can check number of change of signs
hence negative real roots=?