Question

What are the possible number of positive, negative, and complex zeros of f(x) = -2x3 + 5x2 + 6x - 4 ?

a.) Positive: 2 or 0; Negative: 1; Complex: 2 or 1
b.) Positive: 1; Negative: 2 or 0; Complex 2 or 0
c.) Positive: 2 or 0; Negative: 1; Complex: 2 or 0
d.) Positive: 1; Negative: 2 or 0; Complex: 0

Answer 1

If you use Descartes' Rule of Signs and if you put in a negative value, you get 1 sign change, narrowing your answer to "a" or "c". If you put in a positive value, you get 2 sign changes, giving 2 or 0 for positive solutions. But the difference between "a" and "c" is that for a complex solution, they come in pairs, so you can't have "2" or "1", so your answer has to be "c".

Answer 2

Good luck to you in all of your studies and thx for the recognition! @danny562

Answer 3

http://www.youtube.com/watch?v=5YAmwfT3Esc

Answer 4

thank you! i dont want you guys to think im just asking for the answers because the questions i post on here i really just dont get. and i like it when somebody explains it and also gives the correct answer i understand it now! thank you again. @tcarroll010

Answer 5

You are very very welcome! I like that you want explanations! It shows that you are wanting to learn!

Answer 6

ya haha i need the explinations because that does me no good for my tests and final if im just getting the answers.

Answer 7

I really wish all the students here had your very good attitude!