SOLUTION: Arianna needed 140x²+60x square inches of paper to make a book jacket 10x inches tall. In figuring the area she needed, she allowed for a front and back flap. If the spine of

Algebra ->  Test -> SOLUTION: Arianna needed 140x²+60x square inches of paper to make a book jacket 10x inches tall. In figuring the area she needed, she allowed for a front and back flap. If the spine of       Log On


   



Question 1035655: Arianna needed 140x²+60x square inches of paper to make
a book jacket 10x inches tall. In figuring the area she
needed, she allowed for a front and back flap. If the spine
of the book jacket is 2x inches, and the front and back of
the book jacket are 6x inches, how wide are the front and
back flaps? A quotient of polynomials can be used to identify
the answer.
Hello, what is the formula of geometry that applies in this
situation? How can the division of polynomials be used to
find the width?
Problem: http://postimg.org/image/bxw1rg4p7/
ty!

Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!


Arianna needed 140x²+60x square inches of paper to make a book 
jacket 10x inches tall. In figuring the area she needed, she 
allowed for a front and back flap. If the spine of the book 
jacket is 2x inches, and the front and back of the book jacket 
are 6x inches, how wide are the front and back flaps? A quotient 
of polynomials can be used to identify the answer.

(Area) = (length)(width)

(Area) = (140x²+60x)

(length) = the horizontal (left-to-right) dimension 
         = (f+6x+2x+6x+f) =
         = (combine like terms) = (2f+14x)

width = the vertical (top to bottom) dimension = (10x)

Substitute in 

         Area = (length)(width)
  (140x²+60x) = (2f+14x)(10x)

Reverse the factors on the right to make it easier to 
distribute:

  (140x²+60x) = 10x(2f+14x)
    140x²+60x = 20xf+140x²

Subtract 140x² from both sides

          60x = 20xf

Divide both sides by 20x

         %2860x%29%2F%2820x%29%22%22=%22%22%2820xf%29%2F%2820x%29

divide by canceling:

         %28%22%22%5E3cross%2860x%29%29%2F%28cross%2820x%29%29%22%22=%22%22%28cross%2820x%29f%29%2F%28cross%2820x%29%29

         3%22%22=%22%22f

The front and back flaps must be 3 inches wide. 

[Not much division of polynomials is required. Just division
by canceling terms in numerator and denominator.]

Edwin