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) one b) three or one c) two d) two or zero

In order to figure this out you need to use Descartes Rule. I attached a picture showing Descartes Rule.  If the signs changes for when x is positive then the number of times it changes are the possible positive solution. If the sign changes when x is negative then the number of times it changes are the possible negative solutions. With that said the answer is A. View the picture I have attached for the possible + - and imaginary solutions.

Answer = A) One possible positive solution.

None of the options you showed are it.