What is the value?

what will happen if you kept multiplying

\\(1+1/2) \\(1+1/2)(1+1/4) \\(1+1/2)(1+1/4)(1+1/16) \\(1+1/2)(1+1/4)(1+1/16)(1+1/256) \\(1+1/2)(1+1/4)(1+1/16)(1+1/256)......

and so on?

would you get a finite number or an infinite one?

11 Answers

3
Swastika dutta ·

Sir, Should I write the expression in this way:
(1+1/2)(1+1/22)(1+1/24)........

62
Lokesh Verma ·

yes that is a good point to start :)

62
Lokesh Verma ·

btw this is for class IX- X students :P

11
♪doom3 ♫ ·

we would probably get an infinite one, coz as we can rite d eqn as (1+1/2)(1+1/22)(1+1/24)........the power of 2 will then go on increasing like 24,26,28,210.... !!!!

62
Lokesh Verma ·

yes sunit.. that is what it seems .. first look..

but this is not what is happening here...

[1]

The number is actually finite...

look at what swastika has done..

11
♪doom3 ♫ ·

did not get it!!!!

62
Lokesh Verma ·

Hint: FIrst prove:

(a+b)(a2+b2) = (a4-b4)/(a-b)

Then try to do this again and again in this question to see what you get

30
Ashish Kothari ·

Is the value like this:

2x - 1 2x-1

where x is the number of times we multiply the terms.

P.S.: Sir if the value of x is infinitely large, then the value of the expression will also be infinitely large. So, how do we get a finite solution?

62
Lokesh Verma ·

yes asish. that is the answer...

Now you have to try and show that this is finite and infact 2...

1
Maths Musing ·

taking the limits finishes this off , doesn't it ? but i don't think we should use limits , as this is for IX - X

62
Lokesh Verma ·

yes we shouldnt use limits as a phrase.. but as a simple fact.. that the given sum is actually equal to

2 - 12n-1

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