Which of the following expresses the possible number of positive real solutions for the polynomial equation shown below?

5x^3+x^2-7x+28=0
A. Zero
B. Two or zero
C. Three or one
D. One

Question

Which of the following expresses the possible number of positive real solutions for the polynomial equation shown below?

5x^3+x^2-7x+28=0
  A. 	Zero
  B. 	Two or zero
  C. 	Three or one
  D. 	One

anonymous · Answer

http://en.wikipedia.org/wiki/Descartes'_rule_of_signs

anonymous · Answer

if u plug in 0 it = 28 - so 0 is not a solution nor B
use factor rule to find if 2 or 1 
try f(-1) and f(-3)

anonymous · Answer

'if 3 or 1'  i should have wrote

anonymous · Answer

Its asking for the possible number of POSITIVE real solutions...

If you apply Descartes rule of signs you will get the answer B.
But try it yourself..

anonymous · Answer

http://www.wolframalpha.com/input/?i=5x^3%2Bx^2-7x%2B28%3D0 1 negative real and two imaginary roots respectively.