Binomial Expansion: Coefficient of p4q7 in (2p-q)(p+q)10

[look416]

Homework Statement

Determine the coefficient of p⁴q⁷ in the expansion of (2p-q)(p+q)¹⁰

Homework Equations

The Attempt at a Solution

sry, i can't attempt to solve this coz i don't even know how to expand this using formula

 

[rock.freak667]

Do you know how to expand (a+b)ⁿ using the binomial expansion?

 

[look416]

well i know
but does this related to (a+b)ⁿ

 

[look416]

extremely required help

 

[rock.freak667]

well i know
but does this related to (a+b)ⁿ

extremely required help

because you can expand out (p+q)¹⁰ and you can multiply out the terms which will give you p⁴q⁷

 

[lanedance]

might help, to see what rockfreak is implying, if you write it as
(2p)(p+q)¹⁰ - q(p+q)¹⁰

now think about which terms you need to look at for p⁴q⁷

 

[look416]

might help, to see what rockfreak is implying, if you write it as
(2p)(p+q)¹⁰ - q(p+q)¹⁰

now think about which terms you need to look at for p⁴q⁷

well that one is definitely wrong
because (2p-q)(p+q) is not equal to (2p)(p+q) - q(p+q)

 

[look416]

because you can expand out (p+q)¹⁰ and you can multiply out the terms which will give you p⁴q⁷

well no other methods?
because this method will definitely cause a lot of hardwork

 

[lanedance]

well that one is definitely wrong
because (2p-q)(p+q) is not equal to (2p)(p+q) - q(p+q)

really? try multiplying both sides out

 

[lanedance]

well no other methods?
because this method will definitely cause a lot of hardwork

if you use the binomial expansion theorem, this will tell you what the terms are without doing all the multiplication. do you know what the binomial expansion theorem is?

you just have to decide which terms you want to find - see previous post

 

[lanedance]

have a look at this to find out about the binomial expansion

http://en.wikipedia.org/wiki/Binomial_theorem

 

[look416]

have a look at this to find out about the binomial expansion

http://en.wikipedia.org/wiki/Binomial_theorem

if you use the binomial expansion theorem, this will tell you what the terms are without doing all the multiplication. do you know what the binomial expansion theorem is?

you just have to decide which terms you want to find - see previous post

really? try multiplying both sides out

hay hay hay buddy, chill out
maybe i doesn't know binomial expansion very well, but you don't have react so...
just now i comment you are wrong just because normally the multiplying of two terms are not like that...
just sorry for offended you

 

[lanedance]

no offence, just trying to help out

 

[look416]

if you are not offended that's good
thx for your help
you and rock.freak667's help is much appreciated