The length of a rectangle is 6 cm less than twice its width. Find the dimensions of the rectangle if its area is 108 cm2. Which equation can you use to solve this problem?
2007-12-16 13:39:27 · 3 answers · asked by Lola L 1 in Education & Reference ➔ Homework Help
w(2w + 6w) = 108
w(2w – 6w) = 108
w(2w – 6) = 108
w(2w + 6) = 108
2007-12-16 13:46:42 · update #1
^^^^^^^^those are the choices
2007-12-16 13:46:59 · update #2
let w = width
let 2w - 6 = length
w (2w - 6) = 108
2w^2 - 6w = 108
2w^2 - 6w - 108 = 0
w^2 - 3w - 54 = 0
(w + 6) (w - 9) = 0
w = -6 or 9 (in this case, only positive numbers, so it is 9)
w = 9
2w -6 = 2(9) - 6 = 18 - 6 = 12
the width of the rectangle is 9 cm and the length is 12 cm.
you use the area formula, and FOIL method to solve the problem.
2007-12-16 13:52:14 · answer #1 · answered by happyfacegirlxx 3 · 0⤊ 0⤋
Let L and W be the length and width of the rectangle.
L = 2 W - 6
LW = 108
Substituting...
( 2W - 6 ) ( W ) = 108
2W² - 6W = 108
2W² - 6W - 108 = 0
W² - 3W - 54 = 0
( W + 6 ) ( W - 9 ) = 0
The positive root is W = 9. Then the length L = 12.
2007-12-16 21:45:24 · answer #2 · answered by jgoulden 7 · 1⤊ 0⤋
The third equation
2007-12-16 22:02:32 · answer #3 · answered by momof3 2 · 0⤊ 0⤋