SOLUTION: i need help sketching these A rectangle is three times as long as it is wide. If its length and width are both decreased by 2cm, its area is decreased by 36cm^2. Find its original

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Question 174630: i need help sketching these
A rectangle is three times as long as it is wide. If its length and width are both decreased by 2cm, its area is decreased by 36cm^2. Find its original dimensions. Make a sketch
Found 2 solutions by Mathtut, edjones:
Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
lets call the width W and the Length L.... L=3W
:
A=3W(W).............eq 1
A-36=(W-2)(3W-2)....eq 2
:
take A's value from eq 1 3W%5E2 and plug it into eq 2
:
3W%5E2-36=%28W-2%29%283W-2%29
:
3W%5E2-36=3W%5E2-2W-6W%2B4multiplied right side
:
8W=40combined like terms
:
highlight%28W=5%29cm width
:
highlight%28L=3%285%29=15%29cm length

Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
L=3w
.
Let L be the length, w be the width and A be the original area.
L*w=A
(L-2)(w-2)=A-36
.
Substitute 3w for L in both equations.
3w*w=A
(3w-2)(w-2)=A-36
.
3w^2=A
3w^2-8w+4=A-36
.
3w^2-8w+4=3w^2-36 substitute 3w^2 for A
-8w+4=-36
-8w=-40
w=5
L=15
.
Ed