The sum of the series `1/(1*2)-1/(2*3)+1/(3*4)----` upto `oo` is equal to

The sum of the series 1/1.2 - 1/2.3 + 1/3.4 … upto infty is equal to

the sum of the series (1)/(2!)-(1)/(3!)+(1)/(4!)- upto infinity is

The sum of the series 1/(2!) - 1/(3!) + 1/(4!) - …….. upto infinity is

The sum of the series 1/(2!)-1/(3!)+1/(4!)-... upto infinity is (1) e^(-2) (2) e^(-1) (3) e^(-1//2) (4) e^(1//2)

The sum of the series 1/(2!)-1/(3!)+1/(4!)-... upto infinity is (1) e^(-2) (2) e^(-1) (3) e^(-1//2) (4) e^(1//2)

The sum of the series (1)/(2!)+(1+2)/(3!)+(1+2+3)/(4!)+..to infty is equal to

The sum of the series (1)/(2!)+(1+2)/(3!)+(1+2+3)/(4!)+..to infty is equal to