Find expression for difference in areas of new, old decks

Connie

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Oct 6, 2006
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hi, i became confused when i read this, wat am i supposed to do?

Rick has a deck that is of rectangular shape. its length is three times its width. he decides to enlarge this deck so that the new deck is 6ft longer and 4 ft wider than the original deck. if x represents the original width of the deck, which expression represents the difference between the new deck area and the original deck area?

i got x^2+6x+8 and got it wrong :(
 

Denis

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deck: x by 3x = 3x^2
new deck: (x+4) by (3x+6) = 3x^2 + 18x + 24

So dutifully perform an appropriate subtraction which will diligently provide the anticipated solution :idea:
 

Loren

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Sides of original deck are x and 3x. Sides of expanded deck are x+4 and 3x+6.
Difference between the two areas would be "area of new deck minus area of original deck." Give it another go. You can get it.
 

Connie

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is it 18x+24?
 

Subhotosh Khan

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Denis

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Connie said:
is it 18x+24?
simplifying that to 6(3x + 4) may get you an extra mark...if teacher in generous mood :wink:
 
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