00:01
All right, so they're asking for a function, y equals f of x, such that the derivative is 1 over root x and then f of 9 equals 1.
00:10
So what can i get from the fact that the derivative is 1 over root x? i'm going to write that as x to the negative 1 half, so it's easier to do the reverse power rule.
00:20
And then i'm going to take an anti -derivative.
00:23
So i increase that exponent by 1, go from negative 1 half to positive 1 half, and then i divide by the new exponent.
00:32
So dividing by one half is the same as multiplying by two.
00:35
That's where that comes from.
00:37
And then i need a plus a constant.
00:40
Okay.
00:40
So i've used that piece of information.
00:43
Now i need to use this piece of information...