00:01
We are as to solve the differential equation, y double dash plus 2xy dash minus 5y is equal to 0 using the series method.
00:13
And we are given with some initial conditions and they are y of 0 is equal to 4 and y dash of 0 is equal to 2.
00:24
Now let's consider this equation as equation number 1 and these two as equation number 2.
00:34
Understand that the standard equation can be written as yw dash plus p of x times y dash plus q of x is equal to 0.
00:47
If we compare this equation with equation number 1, we can understand that p of x is equal to 2x.
00:55
And q of x is equal to minus 5.
01:01
Clearly, p of x and q of x are analytic at x is equal to 0.
01:09
So what we can say is x is equal to 0 is the ordinary point.
01:16
Now let's assume y to be equal to summation n runs from 0 to infinity, a .n, x to the power n.
01:27
This will be our equation number 3.
01:30
From here, we can compute the value of y -dash.
01:33
It will be equal to summation n runs from 1 to infinity, n times a .n times x to the power n minus 1.
01:45
And similarly, we can compute the value of y double -dash.
01:48
It will be equal to summation n runs from 2 to infinity, n times n plus 1 times a .n times x to the power n minus.
02:00
2.
02:01
From these equation we can get that.
02:07
Summation n runs from 2 to infinity n times n minus 1 times a x to the power n minus 2 plus 2 x times summation n runs from 1 to infinity.
02:23
N times a n times x to the power n minus 1 minus 5 times summation n runs from 0 to infinity .m 5 times summation n runs from 0 to infinity .m...