option c...... simple trick is that put only n=o,then we see that all term become zero.which only in case option c.so don't waste your time use short trick.
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15 comments:
option C....just take 4 as common and take the g.p of the terms ... we will get the answer..
It's C
Its just as easy as substituting value of 'n' and checking options.
if it is right post me...
yaaa checking is easy... bt we can do it through process also
ya from my knowledge answer is "c"! but i have doubt on this?
dude may i know what is that?
yah it is C because it is in the geometric progression
hey after a stong confirmation i found the right answer the same option "C"
option c......
simple trick is that put only n=o,then we see that all term become zero.which only in case option c.so don't waste your time use short trick.
Option C
yaa... put n=o.. den only in c ol terms wil be zero... so ans. is "C"
ans iz c
Answer to this question is option C
this question is very easy.put n=1 then u will get the 4...so option c
sum= 4+44+444+.........+tn
sum= 4+ 44+.........+tn-1+tn
subtracting above two equations we get
0=4+40+400+.............+(tn-tn-1)-tn
tn=(4+40+400+...n terms)
tn=4*(10^(n)-1)/(10-1) -- G.P summation
sum=sigma of tn
sum=4/9*(sigma of 10^(n)-sigma of 1)
sum=4/9*[10*(10^(n)-1)/(10-1)-n]
sum=option 'C'
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