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Mathematics 14 Online
OpenStudy (anonymous):

Help

OpenStudy (anonymous):

Have do I come from this \[\sqrt{n^2+nx}-1\] to this \[\Large \frac{\sqrt{1+\frac{x}n}-1}{\frac1n}\]

OpenStudy (souvik):

\[\sqrt{n ^{2}+nx}-1\]=\[\frac{ \sqrt{1+\frac{ x }{ n }}-\frac{ 1 }{ n }}{ \frac{ 1 }{ n } }\]

hartnn (hartnn):

i don't see any way, because those 2 aren't equal

hartnn (hartnn):

what souvik did is correct

hartnn (hartnn):

you want to know how to get there ?

OpenStudy (anonymous):

arrh I mean \[\sqrt{n^2+nx}-n\]

hartnn (hartnn):

then what you wrote is correct

OpenStudy (souvik):

then you are right!

hartnn (hartnn):

can you factor out n^2 from n^2+nx ?

hartnn (hartnn):

no ? then, can you factor out n from n^2+nx first?

OpenStudy (anonymous):

\[\sqrt{n*(n+x)}-n\]

hartnn (hartnn):

no, thats incorrect, factor out 'n' from n+x

hartnn (hartnn):

actually \(\sqrt{n*(n+x)}=\sqrt n \sqrt{n+x}\)

OpenStudy (anonymous):

I cant spot the solution.. :(

hartnn (hartnn):

you got this, right ?? \(\sqrt{n*(n+x)}=\sqrt n \sqrt{n+x}\) now n+x = n*1 + x/n * n = n (1+x/n) clear rtill here ?doubts ?

OpenStudy (anonymous):

I can follow you until here: \[\sqrt{n^2+nx}-n=\sqrt{n*(n+x)}-n=\sqrt{n} \sqrt{n+x}-n\]

hartnn (hartnn):

ok, can you distribute ? a (b+c) = ab+ac what about \(n \times (1+x/n) = ... ?\)

OpenStudy (anonymous):

\[=n+x\]

hartnn (hartnn):

so, i just replaced n+x by that quantity, by 'undistributing' or 'factoring' out the n

OpenStudy (anonymous):

Yes so we have: \[\sqrt{n}\sqrt{n*(1+\frac{ x }{ n })}-n\]

hartnn (hartnn):

\(n+x=(n\times 1+(x/n)\times n)=n(1+x/n)\)

hartnn (hartnn):

yeah, \(\large \sqrt{n}\sqrt{n*(1+\frac{ x }{ n })}-n=\sqrt{n}\times \sqrt n\times \sqrt{(1+\frac{ x }{ n })}-n\) and \(\sqrt n \sqrt n=n\)

hartnn (hartnn):

ok ?

OpenStudy (anonymous):

\[\sqrt{n}\sqrt{n}\sqrt{1+\frac{ x }{ n }}-n=\frac{ \frac{ n*\sqrt{1+\frac{ x }{ n }}-n }{ n } }{ \frac{ 1 }{ n } }=\frac{ \sqrt{1+\frac{ x }{ n }}-1 }{ \frac{ 1 }{ n } }\]

hartnn (hartnn):

you got it! :)

OpenStudy (anonymous):

Thank you.

hartnn (hartnn):

welcome ^_^

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