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Find the sum to n terms of the G.P. 1,-a...

Find the sum to n terms of the G.P. `1,-a,a^2,-a^3,...(ane-1)`

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`a=1, r= -a/1=-a
` `S_n=a(1-r^n)/1-r=1[1-(-a)^n]/1+a=[1-(-a)_x^n]/1+a`
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V PUBLICATION-SEQUENCES AND SERIES-QUESTIONBANK
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