Question

tim a biet a=1/2+1/4+1/8+1/16+....[tong co 10 so hang]

Answer 1

a = 1/2+1/4+1/8+1/16

= (1 - 1/2) + (1/2 -1/4) + (1/4 - 1/8) + ... + (1/512 - 1/1024).

= 1 - 1/1024

= 1023/1024

Answer 2

A=1/2+1/4+1/8+1/16

A=1/2+(1/2-1/4)+(1/4-1/8)+(1/8-1/16)+....+(1/512-1/1024)

=1/2+1/2-1/1024

=1-1/1024=1023/1024

DS : 1023/1024

Answer 3

a = 1/2 + 1/4 + 1/8 + 1/16

= ( 1 - 1/2 ) + ( 1/2 - 1/4 ) + ( 1/4 - 1/8)  + ... + ( 1/512 - 1/1024 )

= 1 - 1/1024

= 1023/1024

Answer 4

A = 1/2 + ( 1/2 - 1/4 ) + ( 1/4 - 1/8 ) + ......... +( 1/512 - 1/1024 )

= 1/2 + 1/2 + 1/1024

= 1 - 1/1024

= 1023/1024

ĐS : 1023/1024