00:01
Okay, we're asked to come up with a possible formula for a curve that goes through two points, 0, 40, and 20, 14.
00:13
Okay, well, we can give a general, since it's curved, we can say y is equal to some quadratic function of x.
00:26
And we want to find a, b's, and c's that would make this work.
00:30
Well, if we plug in the values that we know, when x is equal to 0, y is equal to 40.
00:39
So 40, plugging in x for 0, is going to be equal to a times 0 squared plus b times 0 plus c, or 40 is equal to c.
00:54
C.
00:56
And when we plug the other value in, we have x equals 20 and y equals 14.
01:03
So that would say 14 is equal, so i'm plugging, i'm using this point, and it says 14 is equal to a times 20 squared plus b times 20 plus c, and we know c is 40.
01:21
And so this gives us a relationship between a and b.
01:26
So we could say that, let's do this in terms of b.
01:34
So let's say we have 20b, and we want to put everything on the other side...