18:quad 1+2+3+...+n<(1)/(8)(2n+1)^(2)

.If 20 , 19 1/ 3 , 18 2/ 3 ,,... ,are in A.P.,and sum to 'n' terms of the series is 300 then '2n' is ] , [ 1) 25 2) 50 3) 75 4) 18

If a^(2) + (1)/(a^(2)) = 18 and a ne 0 , find: a^(3)- (1)/(a^(3))

Electronic transition in He ion takes from n_2 to n_1 shell such that : 2n_2 + 3n_1 = 18 , 2n_2 - 3n_1 = 6 What will be the total number of photons emitted when electrons transit to n_1 shell ?

Suppose n is a natural number such that |i + 2i^2 + 3i^3 +...... + ni^n|=18sqrt2 where i is the square root of -1 . Then n is

Suppose n is a natural number such that |i + 2i^2 + 3i^3 +...... + ni^n|=18sqrt2 where i is the square root of -1 . Then n is

Suppose n is a natural number such that |i + 2i^2 + 3i^3 +...... + ni^n|=18sqrt2 where i is the square root of -1 . Then n is

Solve: 18 1/2 - 15 1/3 .

Show that 3C_0-8C_1 + 13C_2 - 18C_3 + ..... + (n+1)^(th) term = 0

The emission spectrum of hydrogen is found to satisfy the expression for the energy change Delta E (in joules) such that Delta E = 2.18 xx 10^(-18)((1)/(n_(1)^(2))-(1)/(n_(2)^(2)))J where n_(1) = 1,2,3,.... and n_(2) = 2,3,4,... The spectral lines correspond to Paschen series if