- #1

zeba255

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**Help with asymptotic expansions, please!**

## Homework Statement

What is the behavior of asymptotic expansion of cosine integral function? Under what conditions should it be valid approximation to Ci(x)

Ci(x)=- ∫∞x (cost/t)dt {in words} (Integral from x to infinity)(cost/t)dt

## Homework Equations

-Intefral x to infinty(e^it/t)dt

## The Attempt at a Solution

I have integrated the functions by part, i got the right answer with the right asymptotic expansion i.e. Ci(x) = (sinx/x)-(cosx/x)-(1.2sinx/x)+(1.2.3cosx/x^4)+R