SOLUTION: The width of a rectangular playground is 2x -5 feet, and the length is 3x +9 feet. Write a polynomial P(x) that represents the perimeter and then evaluate this perimeter polynomial

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: The width of a rectangular playground is 2x -5 feet, and the length is 3x +9 feet. Write a polynomial P(x) that represents the perimeter and then evaluate this perimeter polynomial      Log On


   

Question 268890: The width of a rectangular playground is 2x -5 feet, and the length is 3x +9 feet. Write a polynomial P(x) that represents the perimeter and then evaluate this perimeter polynomial if x is 4 feet
please explain this problem im not really sure what to do with it.
Answer by JBarnum(2146) About Me  (Show Source):
You can put this solution on YOUR website!
The width of a rectangular playground is 2x -5 feet, and the length is 3x +9 feet. Write a polynomial P(x) that represents the perimeter and then evaluate this perimeter polynomial if x is 4 feet


Ok so we know that the Perimeter of a rectangle is Width+Width+Length+Length
in equation form its P=2W%2B2L If W=2x-5 and L=3x+9 then we can find P(x)by using substitution
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P=2W%2B2L
P%28x%29=2%282x-5%29%2B2%283x-9%29 multiply the 2 in to both sets of parenthasies
P%28x%29=4x-10%2B6x-18 Add like terms
P%28x%29=10x-28 this is your equation
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P%28x%29=10x-28 If x=4 then solve for P(x)
P%28x%29=10%284%29-28
P%28x%29=40-28
P%28x%29=12 Perimeter = 12ft
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CHECKING ANSWER
P%28x%29=2%282x-5%29%2B2%283x-9%29
12=2%282%284%29-5%29%2B2%283%284%29-9%29
12=2%288-5%29%2B2%2812-9%29
12=2%283%29%2B2%283%29
12=6%2B6
12=12
CORRECT