How do I find the area

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

If f(x)=3 over x+2 - square root x-3 then f(7)=

Find the simplified product: 2sqrt 5x^3(-3sqrt10x^2) a: -30sqrt2x^5 b: -30x^2sqrt2x c: -12x^2sqrt5x d: -6sqrt50x^5