Evaluation of reduction formula

[charmedbeauty]

Homework Statement

Given ∫xⁿ2^xdx= 2/ln(2) -n/ln(2)∫x^n-12^xdx, for n≥1

find ∫x³2^xdx

all integrals have limits 1and 0.

Homework Equations

The Attempt at a Solution

doing this I get...

2/ln2 -3/ln2(2/ln2-2ln2)(2/ln2 -1/ln2)(2/ln2-1/ln2)

but this just gives me 0

I must be doing something wrong but I don't know what?

 

[Simon Bridge]

Do each step on a different line... you've got your brackets in the wrong places.
It will help you to put k=1/ln(2) ;)

 

[charmedbeauty]

Do each step on a different line... you've got your brackets in the wrong places.
It will help you to put k=1/ln(2) ;)

ok yeah that helped..got it now.:)

 

[Simon Bridge]

Cheers. It's easy to lose track of these things.