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A = L x w

4200 = L x w

L = 4w - 20 ; substitute

4200 = (4w-20)* w

4200 = 4w^2 - 20w

0 = 4w^2 - 20w - 4200

0 = 4 (w^2 -5w - 1050)

(4)(w-35)(w+30)

w = 35 (Disregard -30)

If w = 35, L = 4(35) - 20

L = 140 - 20

L = 120

So L=120ft, w = 35ft

Proof:

120 ft x 35ft = 4200 sq ft , and

120 is (4x35) - 20 YES!!

Hope that helps.

L = 4W - 20 (1)

L*W = 4200 (2)

Sub (1) into (2)

(4W - 20) * W = 4200

4W^2 - 20W - 4200 = 0

W^2 - 5W -1050 = 0

(W - 35)(W + 30) = 0

so W = 35, since you can't have -30 as width.

then sub W = 35 into (1)

L = 4*35 - 20

L = 120

so the length is 120 feet and width is 35 feet

Well, here are the steps.

1.) 4200=x+4x-20 The length is represented by x, and the width is 4x-20, which is the equivelent to 20 feet less than four times its width

2.) 4200=5x-20 Add like terms, which in this case is any number with x as the variable

3.) 4220=5x Get the variable by itself, which means that you have to add 20 to both sides

4.)x=844 Divide both sides by 5 to find x (836 is your length)

5.) (4*844)-20= 3,356 Plug in the length to the equation to find your width, which is 4x-20

6.) Your dimensions are 3,356 ft by 844 ft

The width is w feet.

The length is 4w - 20 feet.

The area is

( w ) × ( 4w - 20 ) = 4200

4w² - 20w = 4200

Subtract 4200 from both sides to set the equation equal to 0

4w² - 20w - 4200 = 0

Divide both sides by 4

w² - 5w - 1050 = 0

Factor, then set the factors equal to zero and solve for w.

let l represent length of lot and let w represent width of lot

l x w=4200

l = 4w-20

substitute equation 2 into equation 1.

(4w-20) x w=4200

4w^2-20w=4200

4w^2-20w-4200=0

w^2-5w-1050=0

now you factor to find w.

w=2.5

sub that in to the original equation.......

l x w = 4200

l x (2.5) =4200

l=1680.

the dimensions are 2.5 feet by 1680 feet.

75.5 by 55.5