00:01
The key to this problem is using the rational root theorem as well as synthetic, we have 2x of the 4th, minus 15x cubed, plus 7x squared, minus x, and then plus 7.
00:25
So what the rational root theorem says is the possible rational roots, i like to write, prr, are the positive and negative factors of the constant.
00:35
So positive negative 1, positive negative 7.
00:38
But you also want to consider factors of the leading coefficient because what could also happen is, you know, factors of the 7 divided by factors of the leading coefficients.
00:51
But doing a little bit of investigation, and this is how i set up synthetic.
00:58
I don't know if your teacher does a little bit differently.
01:00
But if you get a remainder of zero, then what you try in your problem is a root.
01:08
So i did an investigation and saw that 1 works because as i do my synthetic where i add straight down and multiply by what's in the box, 2 times 1 is 2.
01:20
Again, add straight down.
01:22
Negative 15 plus 2 is negative 13, multiply by what's in the box, adding and multiply, adding and multiply.
01:32
I got a remainder of 0...