00:01
In this question, we want to express the given quantity as a function f of x of one variable x.
00:08
Here they tell us that the product of two numbers, x and y, whose sum is 28.
00:16
So we have a function f of x that we're trying to come up with.
00:22
Well, we know that we have the product of two numbers, x and y.
00:27
So i'm going to call that p to start and say my p is equal to x times y.
00:35
And what do i know? i know x and y have a sum of 28.
00:42
So i know that x plus y is equal to 28.
00:49
And i want to use that constraint to squash this function down from the world of two variables to the world of one variable.
00:59
So how do i do that? i'm going to go to my constraint, x plus y equals 28, and i'm going to solve for y.
01:07
I'll subtract x from each side to get y equals 28 minus x...
