Question

find the number of possible positive real zeros of f(x)=8x^4-72x^3+144x^2.

Answer 1

We will need Descartes' Rule of Signs.

Answer 2

and the second question and last is find the discriminant of -3x^2-4x+6=0

Answer 3

Let's do this first.
Read up on Descartes' Rule of Signs.
http://www.purplemath.com/modules/drofsign.htm