Quick polynomial question (1 Viewer)

[nrlwinner]

I'm just wondering. What's the best way to determine whether a polynomial in its factor form is positive or negative.

eg.

 

[Aerath]

I'm not quite sure what you mean....
If I could hazard a guess, you're pretty much asking when> 0

Well (1-x)^4 is always positive. So, the sign of the polynomial is dependent upon (3-2x)(x+3). If you draw the graph (3-2x)(x+3), you'll find it is negative when x<-3, or x> 3/2, and it is positive -3<x<3/2

 

[Fortify]

Well it'll be:

(-2x) * (-x)^4 * (x) = -2x^6

So it'll be negative.

Tbh I have no idea.

 

[nrlwinner]

Oh. I mean when you graph it, how do you determine which way the ends point?

 

[shady145]

depending on what degree the polynomial is, but my teacher told me last year if its positive then it always has an end in the 1st quadrant

 

[kaz1]

I look at the largest root which in this case is 3/2. You then sub an easy number greater than that like 2 and see if the result is positive or negative.

 

[shady145]

how do you determine which way the ends point?

like up or down?

 

[Timothy.Siu]

u just find if the largest power of x is positive or negative.
its negative in this case so it would go down.