Question 7208: the width of a rectangle is 3 inches less than its length. the area of the rectangle is 340 square inches. what are the length and width of the rectangle?
thank you!!!!
Answer by prince_abubu(198)   (Show Source):
You can put this solution on YOUR website! "The width of the rectangle is 3 inches less than it's length" translates to w = l - 3. The length is longer, so it needs to be knocked off by 3 to equal the shorter w.
Since l*w = area, our equation will be  which is expanded to  . We need to transfer the 340 to the left side so that the right side will be equal to zero. We now have 
We now have to factor that equation so that it will look like a (x ± ?)(x ± ?) = 0. This is a bit tough. What times what = 340 whose sum or difference gives you the -3? It turns out to be -20 and 17 after trial and error. So, our equation now should be  .
As you can see, the solutions are 20 and -17, since either value, when plugged in, will make the equation true. BUT, he have to throw out the -17 because it's negative, and you can't have a negative measure.
So the length turned out to be 20 inches. The width, then, if 3 inches shorter, would be 17 inches.
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