You can
put this solution on YOUR website!Let the length of one side of the square be x:

is the area of the square
Area of the retangle:
(x+6)(x-1)
which is equal to

so if the area of the retangle is twice the area of the square, then we can set up an equation:

Now, slove it:

Now use the quadratic formula to slove:

x = (-4/-2) or (-6/-2)
x = 2 or 3
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Check:
if x=2
x^2 = 4
(2+6)(2-1) = 8
8 = 2*4
8=8 (2 is right!)
if x=3
x^2 = 9
(3+6)(3-1) = 18
18 = 2*9
18=18 (3 is right!)
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So the answer is 2 or 3, they both work!