- #1

TiberiusK

- 24

- 0

## Homework Statement

I must show that t H_n satisfies a diferential equation. By diferentiating H_n(x) = -xH_(n-1)(x) - (n - 1)H_(n-2)(x) (1) and

using induction on n, show that, for n >= 1,

H'_n(x) = -nH_(n-1)(x) (2)

I have to use (2) to express H_(n-1) and H_(n-2) in terms of derivatives of H_n, and substitute these into (1) to show that

H''_n - xH'_n + nH_n = 0 (3)

for n>= 0. Now let O_n(x) = exp(-(x^2)/4 )H_n(x). Using (3) I must show that

O''_n +(n+1/2-(x^2)/3)O_n=0

## Homework Equations

H_n(x) for n = 0,1,2.... : H_0(x) =1 and H_1(x) = -x; then, for n >=2, H_n is defined by the recurrence

H_n(x) = -xH_(n-1)(x) - (n - 1)H_(n-2)(x): (1)

## The Attempt at a Solution

I need some help on getting started ,my first problem is how to differentiate the recurrence

H_n(x) = -xH_(n-1)(x) - (n - 1)H_(n-2)(x) ....because I get

H_n'(x) =-H_(n-1)'(x) -xH_(n-1)(x) - (n - 1)H_(n-2)'(x) =>-H_(n-1)'(x)[1+x]- (n - 1)H_(n-2)'(x) and I do not know how to continue ....