Answers

2016-07-21T19:32:00+08:00
Let l  =  length of pathway
& w = width of of pathway
then 2x + 2y = 90  >  2(x+y) =90    >  x+y = 45    >  perimeter of rectangle
                                                              x =  45-y
and     xy    =  350    >      area of rectangle
         ( 45-y)(y) =  350
           45y-y² -350 = 0            /  . -1
           y² - 45y +350 = 0
       ( y -10)(y-35) = 0
         y = 10    or y =  35
so the length is 35m  &
  the width is 10m......
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2016-07-21T19:55:57+08:00

The area of the concrete pathway is 350m2 and its perimeter is 90m. what is the length of the pathway?

Answer provided by our tutors

we assume that the pathway is rectangular, with some length 'l' and some width 'w'


the area is then "A=lw" and the perimeter is "P=2l+2w"


this gives this system of equations: 

350=lw, so that l=350/w

90=2l+2w


we substitute '350/w' for 'l' and solve for 'w':

90=2(350/w)+2w

and find that 'w' can be either '35' or '10'


this gives two possibilities for 'l':

l=350/35 = 10

l=350/10 = 35


Since this is a pathway, it makes sense that the width is the smaller dimension, giving a width of 10m and a length of 35m

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