Sunday, November 17, 2013

the length of a rectangle is seven more than three times its width. It the perimeters is 38 cm, what is the area in centimeters, of the rectangle.

%0D%0Al=3w%2B7%0D%0A
and
%0D%0AP=2%28l%2Bw%29%0D%0A
and so
%0D%0A38=2%28l%2Bw%29%0D%0A
or...
%0D%0Al%2Bw=19%0D%0A
and so...

%0D%0A%283w%2B7%29%2Bw=19%0D%0A
%0D%0A3w%2Bw%2B7-7=19-7%0D%0A
%0D%0A4w=12%0D%0A
so w=3
and thus l=3w+7=3(3)+7=16
this gives us an area of (3)(16)=48 cm squared

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