Question

The sum of n terms of the series 5/2-1 + 2/5 - ...... is

(a) (1/14) (5"+2")/52 (b) (1/14) (5"-2")/5"2 teboth

(d) None​

Answer 1

Answer:

Common ratio of GP is -2/5

sum of series is

$\frac{ \frac{5}{2}(1 - ( - \frac{2}{5} ) {}^{n} ) }{1 + \frac{2}{5} } = \frac{25}{14} \times( 1 - ( - \frac{2}{5} ) {}^{n} )$