00:01
Hello.
00:03
For this problem, we will be using descartes rule of signs to determine the possible number of real zeros for this function.
00:14
So i think the best way to deal with the rule of signs is to do a problem.
00:23
In order to find the positive real zeros for a function or the number of possible real zeros for a function, descartes ' rule of signs asks us to look for the number of sign changes in the function.
00:41
Now, because everything is positive in this function, we have zero sign changes, which means that we have no real positive zeros.
01:11
Now, to find any real negative zeros, we're going to do the same thing, but instead of looking at f of x, we're going to look at f of negative x.
01:22
So just to show you what i mean, we take our function f and we plug in a negative x wherever we have an x here.
01:31
So i've gone ahead and written that out.
01:33
Let's go ahead and simplify that.
01:34
So f of negative x would be we have negative x cubed, which is just going to be a negative times x cubed.
01:46
When we have negative x squared, that leaves us with a positive.
01:51
So we have two positive, 2x squared...