The sum of first 9 terms of the series. 131+13+231+3+13+23+331+3+5+...
A
142
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B
192
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C
71
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D
96
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Solution
The correct option is D 96 nth term of series =[n(n+1)2]2n2=14(n+1)2 Sum of n term =∑14(n+1)2=14[∑n2+2∑n+1]=14[n(n+1)(2n+1)6+2n(n+1)2+n] Sum of 9 terms =14[9×10×196+18×102+9]=3844=96