Polynomials related Questions by Balaji

  • 8August
  • 2014
  • 12
    6k
    6+24+60+120+210+336+504+720 up to 10 terms is equal to ?

    a) 3680


    b) 4290


    c) 5720


    d) 6170





    answer choice b


    solution


    =n(n+1)(n+2)
    =m^3 - m


    where m = n+1


    sum of all = m(m+1)(m^2+m-2) 


    subs m=n+1
    then put n=10


    =(10*11*12*13)/4
    = 4290
    3/4+5/36+7/144+9/400......19/8100 = ?



    a) 9/10



    b)11/18



    c)99/100



    d)80/81


    answer choice c

    solution



    t= 2n+1/n^2(n+1)^2



      =1/n^2 - 1/(n+1)^2



    whic is nothing but



    (1/1^2)-(1/10^2)



    99/100


     
    1/1*4+1/2*5+1/3*6+1/4*7......1/63*66............... 



    a) 9/17



    b) 7/15



    c) 11/18



    d) 92/173







    answer choice c



    solution



    =1/3 [(1-1/4)+(1/2-1/5)+(1/3-1/6)+...(1/63-1/66)]

    =1/3*11/6

    =11/18