Question 178309
{{{A=LW}}} Start with the area of a rectangle formula



{{{x^2+50x=Lx}}} Plug in {{{A=x^2+50x}}} and {{{W=x}}}



{{{x(x+50)=Lx}}} Factor out the GCF "x" 



{{{(cross(x)(x+50))/cross(x)=(L*cross(x))/cross(x)}}} Divide both sides by "x" to isolate "L". Notice how the "x" terms cancel.



{{{x+50=L}}} Simplify



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Answer:



So the length is {{{L=x+50}}}