This is equal to (x -5)(x - 5), or (x - 5)².
Therefore, using the formula given above, the side's length is equal to (x - 5).
Muliply that by four to obtain the perimeter.
4(x - 5) = 4x -20.
For the second problem, disregard the brackets since there are no other operations besides subtraction and addition.
So it would become 3x^4 -x + 2 + 9x^5 - x² + x.
Now simplify everything and rewrite it in decreasing terms of power,
9x^5 + 3x^4 - x² + 2.
