Question

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

5x³+x²-7x+28=0

a. zero
b. three or one
c. one
d. two or zero

Answer 1

descartes rule of sign for this one yes?

Answer 2

here is a decent explanation
http://www.purplemath.com/modules/drofsign.htm
in your case there are two changes in sign (hope that is clear) so could be two or none

Answer 3

change from
\[x^2\] to
\[7x\] and another change from
\[-7x\] to 28

Answer 4

and then what ?