00:01
In this question, i'm looking to find the domain of the function f of x equals 2x cubed minus 5 over x squared plus x minus 6.
00:10
So we want to know when we're going to have domain restrictions first.
00:16
So we will have restrictions on my domain whenever the denominator is equal to zero, because we're never allowed to divide by zero.
00:26
So we have restrictions when x squared plus x minus 6 is equal to zero.
00:34
Now we're hoping that the quadratic on the left is factorable, and indeed it is.
00:40
I'm going to factor this as the product of two binomials.
00:44
Now in each of the first two slots is going to go x.
00:49
And i am going to look for two numbers, two numbers that multiply to make negative 6, and that add up to make positive 1.
01:02
And if i think about that, i think the two numbers that do that are positive 3 and negative 2.
01:09
Positive 3 and negative 2.
01:12
And if i multiplied out the quantity of x plus 3 times the quantity of x minus 2, i indeed get x squared plus x minus 6...