Question

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

Answer 1

You solve the equation\[\large 2x^3 + 5x^2 - 6x + 4= 0\]Use that link for help.

Answer 2

how would you solve that? factor by grouping wouldnt help

Answer 3

that link isnt giving me the zeros

Answer 4

Type in "2x^3 + 5x^2 - 6x + 4 = 0"

Answer 5

i did, but it didn't give me the complex, negative, or positive zeros

Answer 6

Look through it carefully.
http://www.wolframalpha.com/input/?i=2x%5E3+%2B+5x%5E2+-+6x+%2B+4+%3D+0

Answer 7

I don't see it. Nothing that is relating to the multiple choice answers

Answer 8

Positive: 3 or 1; Negative: 1; Complex: 2 or 0

Positive: 1; Negative: 2 or 0; Complex 2 or 0

Positive: 2 or 0; Negative: 1; Complex: 2 or 0

Positive: 3 or 1; Negative: 0; Complex: 2 or 0

Answer 9

Oops, I forgot to put a negative in there.

Answer 10

http://www.wolframalpha.com/input/?i=+0+%3D+%E2%80%932x3+%2B+5x2+%E2%80%93+6x+%2B+4

Answer 11

Meanwhile, you should learn how to solve cubic equations.

Answer 12

yeah i was hoping someone would teach me on here. I completely forgot

Answer 13

https://www.dpmms.cam.ac.uk/~wtg10/cubic.html

Answer 14

Usually, when you are asked what is the possible number (ie not what are the roots, just how many) it usually means to use Descartes Rule of Signs which gives
3 or 1 positive, no negative and complex by difference....