Question 508723
l=length
w=width
{{{l=2w}}} (length equals twice the width)
area
{{{l*w=48}}}
plug in 
{{{l=2w}}}
{{{2w*w=48}}}
Solve
{{{2w^2=48}}}
Divide
{{{w^2=24}}}
Sqrt
{{{w=sqrt(24)}}}
Simplify
{{{w=2sqrt(6)}}}
Solve for l
{{{l=(2sqrt(6))/2}}}
{{{l=sqrt(6)}}}

Perimeter 
{{{2l+2w}}}
{{{2(sqrt(6))+2(2sqrt(6))}}}
{{{6sqrt(6)}}}