00:01
So we have a function to model the distance away from some place that dion is walking.
00:06
So this is a function where we input time and output distance from tom'sville.
00:20
That means that the inverse function is going to do the opposite.
00:24
We're going to input distance from tom'sville, and we're going to output time.
00:33
And we need to make sure we formulate that the right way.
00:37
D of t is telling us at time t, what is our distance from tom'sville? t inverse of t is telling us that what distance from tom'sville, or at what time will we be a certain distance from tom'sville.
00:54
So we input, let's say we five kilometers and output how much time it's going to take to walk to the point where we are five kilometers from tom'sville.
01:06
So on these answer choices we have, we want one where we input distance and output time.
01:16
It looks like a is the right choice.
01:21
Yep.
01:22
For b, we want to find the explicit inverse function.
01:27
Well, we know first if we input something, we would need to divide by negative 5 and then subtract 15 .5.
01:36
So the inverse of, i guess we're using x, should be x over minus x over 5 .5, minus 15 .5.
01:57
And we can check this d inverse of d of t.
02:02
It's d inverse.
02:13
And we have made a mistake here.
02:22
It's going to be minus x plus 15...