
David G. answered 09/05/20
Certified New York State 7-12 Mathematics Teacher
Let x=a side of the square field
Since the field is a square, x represents both the length and the width
Since the length of the garden will be 4 feet less than the length of the square field, the length of the garden is represented by (x-4)
The width of the garden is 8 less than the width of the field, so it is represented by (x-8)
Area = length * width
Area of garden = 192 ft2
Length = (x-4)
Width = (x-8)
192 = (x-4) * (x-8) Distribute
192 = x2 - 8x - 4x + 32 Subtract 192 from both sides to set equation equal to 0
x2 - 12x - 160 = 0 Can factor equation by grouping or use quadratic formula to solve for x
x2 - 20x + 8x - 160 = 0
x * (x - 20) + 8 * (x - 20) = 0
(x + 8) * (x - 20) = 0
x + 8 = 0 x - 20 = 0
x = -8 x = 20
Reject the negative because a length or width of a garden can't be negative
x = 20
Side of square field = 20
Dimensions of the garden are:
Length = x-4 = 20 - 4 = 16
Width = x-8 = 20 - 8 = 12
The dimensions of the garden are 16ft x 12ft