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Me complete this proof! prove that a quadrilateral is a square. me with the steps for this proof.

Is this a polynomial function? i need to know asap

The area of a rectangle is 10 cm^2. one side of the rectangle is x cm. express the perimeter of the rectangle in terms of x and show that this rectangle cannot have a perimeter of 12 cm. the perimeter of the rectangle in terms of x is __ cm