Simplify the question using indices

Can someone check if i did this correct. it’s number 4 if you’re wondering.

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

What is the value of the discrimination for the quadratic equation 0=×2+2+×2