#### Answer

8 units

#### Work Step by Step

Lets assume that the side of square = x
As we know the area of square = side * side = $x^{2}$
Perimeter of square = 4* side = 4x
by given condition $x^{2}$ - 4x=32
$x^{2}$ - 4x - 32 = 0
$x^{2}$ - 8x +4x -32 = 0
x(x-8) +4(x-8)=0
(x+4) (x-8) = 0
x+4 = 0
x = -4
x-8 = 0
x =8
The length of the square cannot be negative so length of the square is 8 units.