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

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

mertsj · Answer

There are 2 sign changes so...

mertsj · Answer

Do you know the answer to the question I posed?

anonymous · Answer

so is it d? 

let me check it out.

mertsj · Answer

There would be 2 or 0 positive roots. 
f(-x) = -5x^3 +x^2 +7x +28 
There is one sign change so there could be 1 negative root.  That makes a grand total of 3 or 0 real roots.

anonymous · Answer

you mean 3 or 1 real roots? b.

mertsj · Answer

Yes.  sorry

anonymous · Answer

dang it said the answer was d.

mertsj · Answer

Oh of course!!!  It asked for only the POSITIVE ones.  Should have read more carefully.

mathmate · Answer

"...total of 3 or 1 real roots."