Basic Equation question

Question

This is regarding algorith complexity, but that's not the point here.

I saw this resolution:

4( n/1,3 )² = 4/1,69 x n²

Could anyone clarify how is this equation is done? How can 4( n/1,3 )² equals to 4/1,69 x n²

I tried to reproduce but failed drastically.

4( n/1,3 )²  =  4 x n/1,3 x n/1,3
             =  4 x n²/1,69
             =  ?

Thanks in advance.

What is wrong with $4 \times n^2/1.69 = 4/1.69 \times n^2$? – angryavian Aug 31 '14 at 19:09 — angryavian, Aug 31 '14 at 19:09

score 0 · Answer 1 · answered Aug 31 '14 at 19:54

0

$$ (a+b)^2=a^2+b^2+2ab \\(1.3)^2=(1+0.3)^2=1+(0.3)^2+2(1)(0.3)\\(1.3)^2=1+0.09+0.6=1.69 \\so\\4(\frac{n}{1.3})^2=4*\frac{(n)^2}{(1.3)^2}=4*\frac{n^2}{1.69} $$

answered Aug 31 '14 at 19:54

Khosrotash

24,922

Thanks. But how can 4 * n²/1.69 = n² * 4/1.69 – Frederico Aug 31 '14 at 20:18
ab=ba commutative law – Khosrotash Sep 01 '14 at 12:53

Basic Equation question

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