00:01
Okay, here i want to find an exponential function.
00:04
In other words, y equals a, b, power of x, which fits these two points.
00:14
So in other words, find a and b.
00:16
Well, let's plug in the first two points, negative one per x, and y is three quarters.
00:24
So a, b, power of...
00:30
Now, let's repeat that with the second point.
00:34
We have 1, 92 for y is ab.
00:42
Here then what we have are two equations and two unknowns.
00:47
I can solve together and define ab.
00:50
To do that, the best way is to divide the second one.
00:54
Divide ab cubed by ab negative 1.
01:00
Ab cube is 192, ab negative 1 is 3 quarters.
01:06
To divide by second equation by the first.
01:14
So then what happens, the a is cancelled out.
01:21
B cubed over b negative 1 becomes b power 4.
01:26
Second law of exponents, subtract 3 minus minus 1 equals, and we have here in a calculator 192 divided by 3 quarters, so 0 .75 in a calculator, gives me 2, 5, 6, which means i can work out the value of b...