00:01
In this question, we're told that the demand function is c times e to the k x.
00:07
And we are given that p of 800 is 45 and p of 1 ,500 is 40.
00:12
And we are asked to find the constants c and k.
00:17
So from the first condition, p of 800 equals to 45.
00:23
On the other hand, if we plug in x equals 800 in the equation for p, we're going to get c times e to the x.
00:31
Now if we plug in x equals 1500, we are going to get c times e to the 1500k and this gives us a system of equations for finding c and k.
00:48
C times e to the 800k equals to 45 and c times e to the 1500k equals to 40.
01:03
What we are going to do now is solve the equation for the first equation for c to get c equals to 45 divided by 8 e to the 800k.
01:19
And plug in in the second equation.
01:23
In the second equation, we are going to get 45 divided by e to the 800k, multiplied by e to the 1 ,500k equals to 40.
01:38
Then e to the 1500k over e to the 800k simplifies to e to the 1500k minus 800k then we can divide both sides by 45 and simplify the exponent to get e to the 700k equals to 40 over 45 and that simplifies to 8 over 9 now we will rewrite the in equivalent form using logarithms, then by the properties of logarithms, a l 'n of e to the 700k equals to 700k, and from that equation, k equals to a length of 8 over 9 divided by 700, and that's approximately, that's approximately negative 0 .30 -160's and 60 negative 0 .3 zeros and 1683.
03:22
So we found the value of k and now we can use it to find the value of c from this formula.
03:31
C equals to 45 divided by e to the 800k.
03:44
And here we will use the exact value of k, ln of 8 over 9 divided by 700.
03:55
Then we can cancel two zeros.
03:59
So we are going to get a c equals to 45 over e to the 8 ln 8 over 7.
04:10
8 over 7, ln of 8 over 9.
04:17
This is approximately e to the 8 over 7 multiplied by ln of 8 over 9.
04:45
All right, so that's going to be approximately 51 .4840.
05:02
51 .484.
05:14
So this is approximate value of the constant c, and therefore the demand equation is p equals to c multiplied by e to the power, kx.
05:33
And we just found that k equals to negative 0 .30s 16 .83x...