How to expand expression using binomial theorem?

[rahul.6sept]

Dear Sir,

I want to expand an expression using binomial theorem as given below:

(1+E*N[SUB]i1[/SUB]+E[SUP]2[/SUP]*N[SUB]i2[/SUB])[SUP]-2[/SUP]

Since there are three terms with a negative power, I'm not quite sure as how to expand the same.

Regards,

Rahul

 

[barry]

I'm not a math guy, but I think the binomial theorem applies to binomials; you've got a trinomial.

 

[c_mitra]

Group the 2nd and third term together and call that x. Then you have (1+x)^(-2). The general formula for this expansion is:

1-2*x+3*x^2-4*x^3-4*x^4....

This is an infinite series. Look up wolframalpha for the details and other forms of this series. If the second and third terms are small (<<1), then perhaps you can keep the first term only as an approx.

 

[barry]

Group the 2nd and third term together and call that x. Then you have (1+x)^(-2). The general formula for this expansion is:

1-2*x+3*x^2-4*x^3-4*x^4....

This is an infinite series. Look up wolframalpha for the details and other forms of this series. If the second and third terms are small (<<1), then perhaps you can keep the first term only as an approx.

Darn, after thinking a bit, I was just going to suggest grouping two terms!