Question

tính nhanh:

M= 2/3.5 + 2/5.7 + 2/7.9 + ..... + 2/97.99

Giúp mình nhé!

Answer 1

M = 1/3 - 1/5 + 1/5 - 1/7 + 1/7 - 1/9 + ..... + 1/97 - 1/99

M = 1/3 - 1/99

M = 32/99

Answer 2

M=1/3-1/5+1/5-1/7+1/7-1/9+...+1/97-1/99

=1/3-1/99

=32/99

Answer 3

Ta có M= 2/3*5+2/5*7+2/7*9+...+2/97*99

            = 1/3-1/5+1/5-1/7+1/7-1/9+...+1/97-1/99

            = 1/3+(1/5-1/5)+(1/7-1/7)+...+(1/97-1/97)-1/99

            = 1/3 - 1/99

            = 32/99

Vậy M= 32/99