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Find the coefficient of

x^{7} in (1+x+x^2+..+x^7+x^9-x)^{11}
correct answer with proper and full solution please
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1+x+x^2+..+x^7+x^9-x=1+x^2+x^3+,,x^7+x^9 \\ =1+x^2+x^3(1+x^2)+x^4(1+x^2)+x^7(1+x^2) \\ =(1+x^2)(1+x^3+x^4+x^7)=(1+x^2)(1+x^3)(1+x^4)
So for coefficent of x⁷ 
     x^4 from  (1+x⁴)¹¹ and x³ from (1+x³)¹¹
    x⁴ from (1+x²)¹¹ and x³ from (1+x³)¹¹   
2 5 2


hope it helped u if yes mark as the best

0 0 0
sorry but the answer didnt came so please anyone delete it
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