Question 1128052
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<pre>
x*(3x - 13) = 338


3x^2 - 13x - 338 = 0


{{{x[1,2]}}} = {{{(13 +- sqrt(13^2 -4*3*(-338)))/(2*3)}}} = {{{(13 +- 65)/6}}}.


Only positive root is meaningful:  x = {{{(13 + 65)/6}}} = 13.


Thus the width is 13 mm;  the length is  13*3 - 13 = 26 mm.


The perimeter = 13 + 26 + 13 + 26 = 78 mm.     <U>ANSWER</U>
</pre>

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My understanding is that not only an answer does matter - the solution (I mean the correct and correctly presented solution) does matter, too.


It is why I wrote this post after the post by @Mtrkcrc.