Answer:
Perimeter = 4x + 6
Step-by-step explanation:
The area of a rectangle is given by:
Area = L * W
Where L is the length and W is the width.
In this case, we need to factorate the area to find L and W:
Area = x^2+3x-40
Making Area = (x + a)*(x + b), we have:
a * b = -40
a + b = 3
Solving this system, we have a = 8 and b = -5
So we have Area = (x + 8)*(x - 5)
So Length = x+8 and Width = x-5
Perimeter = 2*L + 2*W = 2x + 16 + 2x - 10 = 4x + 6
