00:01
Okay, so when you're asked to evaluate or simplify f minus g of x, what they're pretty much saying is do f of x and subtract off g of x.
00:11
Well, now i'm going to substitute in here that f of x is x minus 5.
00:17
So that thing is x minus 5.
00:21
And g of x is 4x minus 2.
00:27
And what you need to remember as you're subtracting is to distribute.
00:32
That minus into the problem.
00:35
So that's why this first answer is x minus 4x is negative 3x.
00:40
This is really negative 5 plus 2 to give you negative 3.
00:45
So that's that first answer.
00:48
The next one where they're asking you to do f times g, just like in the first one, it's really asking you to do f of x times g of x and so what's important about this one is a so f of x is still x minus five and g of x is still 4x minus two but you need to distribute each piece so you're looking at 4x squared minus 2x and then distribute the negative 5 in there so it's minus 20x and negative 5 times negative 2 is a positive 10 and so this final answer when you combine like terms is negative 20 2x plus 10...