1
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The function f(x) is defined as f(x) = 49 - (x ^2).

2
00:00:06,644 --> 00:00:09,646
Find the value of f(5).

3
00:00:09,646 --> 00:00:10,949
So whenever you're dealing with a function,

4
00:00:10,949 --> 00:00:12,373
you take your input -- in this case,

5
00:00:12,373 --> 00:00:14,573
our input is going to be our 5.

6
00:00:14,573 --> 00:00:17,062
We input it into our little function box,

7
00:00:17,062 --> 00:00:20,371
and we need to get our output.

8
00:00:20,371 --> 00:00:23,111
And they define the function box here as

9
00:00:23,111 --> 00:00:25,648
whatever your input is, take that, square it,

10
00:00:25,648 --> 00:00:28,302
and then subtract it from 49.

11
00:00:28,302 --> 00:00:31,013
So f(5) ...

12
00:00:31,013 --> 00:00:32,583
Every time I see an x here,

13
00:00:32,583 --> 00:00:35,752
since f(x) is equal to this, every time I see an x,

14
00:00:35,752 --> 00:00:37,487
I would replace it with the input.

15
00:00:37,487 --> 00:00:41,560
So f(5) is going to be equal to 49 minus ...

16
00:00:41,560 --> 00:00:45,315
instead of writing x^2, I would write 5^2.

17
00:00:45,315 --> 00:00:49,622
So this is equal to 49 – 25.

18
00:00:49,622 --> 00:00:55,902
And 49 - 25 is equal to 24.

19
00:00:55,902 --> 00:00:57,322
And we are done.