The length of a rectangle is 1m less than twice its width, and the area of the rectangle is 78m^2. Find the dimensions of the rectangle.
Length: ?
Width: ?

Question

The length of a rectangle is 1m less than twice its width, and the area of the rectangle is 78m^2. Find the dimensions of the rectangle.
Length: ?
Width: ?

anonymous · Answer

length = L
width = W

L= 2*W-1

L*W= 78

// plug in 2*W-1 for L in the equation (L*W) = 78

solve for W to find the width.  post what you get for W.

anonymous · Answer

I think I got it after that.

anonymous · Answer

good to hear

anonymous · Answer

I got -6 and 13/2 but you can't have a negative dimension correct?

anonymous · Answer

yes, it is impossible to have a negative length.

L= 2*W-1

L*W= 78

(2W-1)*(W) = 78

2W^2-W = 78

2W^2-W -78 = 0

quadratic formula.

b = -1
a = 2
c = -78

x = [-(-1) +- sqrt((-1)^2-4*(2)(-78))]/(2*2)

x = [1 +- sqrt(1+624)]/4

x = [1+- 25]/4

x = (1+25)/4  OR x = (1-25)/4

x = 6.5  OR -6

x = 7.25

anonymous · Answer

the last x = 7.25 is a typo, it should be 6.5