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 one year ago
\[\lim_{x \rightarrow 1}\frac{ 2x+3x^2........+(n+1)x^n  \frac{ n(n+3) }{ 2 } }{ x1 }\]
 one year ago
\[\lim_{x \rightarrow 1}\frac{ 2x+3x^2........+(n+1)x^n  \frac{ n(n+3) }{ 2 } }{ x1 }\]

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Aryang
 one year ago
Best ResponseYou've already chosen the best response.0what is that written ? n(n+3)/2 ?

shubhamsrg
 one year ago
Best ResponseYou've already chosen the best response.0did you try LH rule?

Aryang
 one year ago
Best ResponseYou've already chosen the best response.0seems legitimate to me..

AravindG
 one year ago
Best ResponseYou've already chosen the best response.0did u get the answer ?

experimentX
 one year ago
Best ResponseYou've already chosen the best response.1dw:1357836283297:dw

experimentX
 one year ago
Best ResponseYou've already chosen the best response.1the derivative is \[ \frac{n x^{1+n}}{1+x}+\frac{2 x \left(1+x^n\right)}{1+x}\frac{x^2 \left(1+x^n\right)}{(1+x)^2} \]

ash2326
 one year ago
Best ResponseYou've already chosen the best response.0We could find the sum of this first and then apply L'Hospital's \[2x+3x^2+....(n+1)x^n\]

experimentX
 one year ago
Best ResponseYou've already chosen the best response.1looks like we could use this formula directly http://planetmath.org/ArithmeticGeometricSeries.html

ash2326
 one year ago
Best ResponseYou've already chosen the best response.0\[S=2x+3x^2+...(n+1)x^n\] \[xS=2x^2+3x^3....(n+1)x^{n+1}\] \[(1x)S=2x+\underline{x^2+x^3+x^4....+x^n}(n+1)x^{n+1}\] This is GP

experimentX
 one year ago
Best ResponseYou've already chosen the best response.1the sum would be http://www.wolframalpha.com/input/?i=differentiate+%28x^2+%28x^n1%29%2F%28x1%29%29 that's you would get indeterminate form ... you can apply L'hopital rule after that

experimentX
 one year ago
Best ResponseYou've already chosen the best response.1you should be getting \[ \frac{1}{3} n \left(2+3 n+n^2\right) \] or since you know you get indeterminate form ... you could apply L'hopital rule from the start. that's way easier.

experimentX
 one year ago
Best ResponseYou've already chosen the best response.1this is equal to http://www.wolframalpha.com/input/?i=Sum[n%28n%2B1%29%2C+{n%2C+1%2C+n}]&dataset=&equal=Submit

Taufique
 one year ago
Best ResponseYou've already chosen the best response.1where is you confusion in this question??

Taufique
 one year ago
Best ResponseYou've already chosen the best response.1Apply Lhospital Rule...differentiate numerator and denominator with respect to variable which is x here ... dw:1358023261199:dw dw:1358023336162:dw

Yahoo!
 one year ago
Best ResponseYou've already chosen the best response.02+ 6 + 12 ............... = n(n+1)

Taufique
 one year ago
Best ResponseYou've already chosen the best response.1my picture is not clear here.. now dw:1358023498420:dw

Taufique
 one year ago
Best ResponseYou've already chosen the best response.1dw:1358023535161:dw

Taufique
 one year ago
Best ResponseYou've already chosen the best response.1dw:1358023576877:dw

Taufique
 one year ago
Best ResponseYou've already chosen the best response.1dw:1358023654085:dw
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