SOLUTION: A rectangular pen has a length of 3 feet greater than its width. If both dimensions are increased by 5 feet, which expression gives the resulting increase in area? a. 10x + 40

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Question 197872: A rectangular pen has a length of 3 feet greater than its width. If both dimensions are increased by 5 feet, which expression gives the resulting increase in area?
a. 10x + 40
b. 13x + 40
c. x2 + 13x + 40
d. x2 + 10x =40
My attempt: area = length x width
original pen would be x(x+3)=x2+3x
new pen would be (x+5)(x+8)=x2+13x+40
However answer sheet says correct answer is A.
Thank you

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
What they're asking for is: "How much bigger
is the 2nd pen than the 1st?
So, in words
Difference = (area of 2nd pen) - (area of 1st pen)
A%5B1%5D+=+x%2A%28x%2B3%29
A%5B2%5D+=+%28x%2B5%29%2A%28x+%2B+8%29
A%5B2%5D+-+A%5B1%5D+=+x%5E2+%2B+13x+%2B+40+-+x%5E2+-+3x
A%5B2%5D+-+A%5B1%5D+=+10x+%2B+40