ARITHMETIC SEQUENCE AND ALGEBRA

  • writing algebraic form of Arethemetic sequence [ nth term }

    6,10,14

    Xn = dn + (f-d)

    Xn = 4n + ( 6-4)

  • Xn = 4n + 2

  • finding d and f in algebraic form

    if , Xn = an + b

    common differ d = a

    first term f = a+b

  • SUM(Sn)

    Sn = n/2 ( f + Xn )

    n = no. of terms

    f = first term

    Xn = last term

  • 10 , 14 , 18 sum of ten terms

    Sn = n/2 (f+Xn )

    = 10 /2 ( 10 + 46 )

    = 5×56

    =280

  • Algebraic form of the sum

    Sn = d/2 n2 + ( f - d/2 ) n

    5,9,13 ……algebric form of sum

    = 4/2 n2 + (5 - 4/2 ) n

    =2 n2 + 3n

  • Sn = a n2 + b n

    d = 2 a

    f = a+ b