00:01
Approximate 7 .9 to the two -thirds.
00:03
And i'm not sure if the function is f of x is x to the two -thirds, or f of x equals 8 minus x to the two -thirds.
00:15
See, i'm going to do them both at the same time.
00:18
Okay, f of x is approximately equal to f of a plus f prime at a, x minus a.
00:29
So in the first one, a is eight, and the second one, a is 0.
00:37
So f of a is 8 to the 2 thirds, which is the cube root of 8 squared, 4.
00:44
And over here, f of a is 0 to the 2 thirds, which is 0.
00:52
F prime of x is 2 thirds, x to the minus 1 third, or 2 over 3, x to the 1 3.
01:02
And here, f prime of x is two thirds, eight minus x to the minus one third times minus one.
01:15
So minus two over three, eight minus x to the one third.
01:24
Okay, f prime at a, that's f prime at eight.
01:30
That is two over three times eight to the one third.
01:35
Cube root of 8 is 2 so that's 2 over 6 which is 1 3rd and here f is 0 i mean a is 0 so f prime at a is f prime at 0 which is minus 2 over 3 times 8 to the 1 3 which is minus 1 3 which is minus 1 3.
02:01
Okay, so f of x is approximately 4 plus one -third x minus 8.
02:14
And here, f of x is approximately 0 minus 1 -third x minus 0.
02:28
So minus 1 -third x for this one.
02:32
So then what were we trying to find? i forgot 7 .9...