# Homework Help: Solving 3rd order Polynomial

1. Nov 16, 2004

### assman

5x^3 - 2x^2 + 3

Where are the zeros. Is there one between [-1,1]

THanks.

2. Nov 16, 2004

### UrbanXrisis

There is a zero at (-0.7860031,0)

3. Nov 16, 2004

### Justin Lazear

Evaluate the expression at x = -1 and x = 1.

What are the signs of the expression at these two points? What does this tell you about whether or not there is at least one root between them (hint: plot the two points and draw a line through them. Does it cross 0?) ?

--J

4. Nov 16, 2004

### dduardo

Staff Emeritus
UrbanXrisis, that is the wrong answer.

5. Nov 16, 2004

### UrbanXrisis

ACK! Sorry! (-0.7290014,0) Typed in the wrong answer

6. Nov 16, 2004

### Tom McCurdy

The easiest way to solve that for you might be to graph the equation. Then limit you window from in the x from -2 to 2 then see if it crosses the axis between -1 and 1... zoom out to see all the zeros if more exist.

7. Nov 18, 2004

### Raza

I think x would -0.92 if it is like this
5x^3 - 2x^2 + 3=0