When u skip count by 8 you skip over the secret number

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

Given δjkl : δxyz, find x. a)10 b)12 c)16 d)20

(-y to the power of 2 - 4y- to the power of 2 -6 y +3)