Prev

Next

Q65 of 74 Page 9

Find the sum of the following series upto n terms:1 × 2 + 2 × 3 + 3 × 4 + 4 × 5+……

Let T_n denotes the nth term of the given series

T_n = [nth term of 1, 2, 3 …..] × [nth term of 2, 3, 4 …..]

= [1 + (n – 1) 1] [2 + (n – 1) 1]

= n(n + 1)

T_n = n² + n

S_n = ∑ n² + ∑ n

=

=

    =
    =
    =
    =

More from this chapter

63

What will Rs. 500 amounts to in 10 years after its deposit in a bank which pays annual interest rate of 10% compounded annually?

64

If A.M. and G.M. of roots of a quadratic equation are 8 and 5 respectively, then obtain the quadratic equation.

66

Find the sum of the following series upto n terms 1 × 2 × 3 + 2 × 3 × 4 + 3 × 4 × 5 +…….

67

Find the sum of the following series upto n terms 3 × 1², 5 × 2², 7 × 3²,……..