00:01
So what i did with this problem is i went to my graphing calculators, typed in, so like right here, x equals n8 .1, my graph looked like this kind of go this way, and they tell you rational zero.
00:12
If i were guessing what this would be, based of the numbers they give, that x is equal to 6q plus x square, 12x5, is, first of all, that that is a negative number.
00:26
Know the rational root theorem, it has to be factors of the constant divided by factors of the coefficient.
00:31
So i'm going to guess negative five -sevenths.
00:36
And what that means is i would probably do a long division, just because a long division makes more sense to me.
00:48
So let's circle this and see if it actually works.
00:52
I like to multiply seven and then add five to the left side.
00:57
So if that really is 0, if i do long division, divide 6 cubed plus 12 squared, plus of x plus 5, i'll give you a remainder of 0.
01:08
Let's see.
01:10
6x squared gives me 7x cubed, but i'll multiply 5.
01:14
And then when i act down, the 1 i get 7x squared plus 12, just bringing down.
01:20
So times an x will give me 7x squared again, and then plus 5x...