SOLUTION: The printed matter on a 16 by 20 centimeter page of a book must cover 192 square centimeters. If all margins are to be the same width, how wide should they be?

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Question 190806: The printed matter on a 16 by 20 centimeter page of a book must cover 192 square centimeters. If all margins are to be the same width, how wide should they be?
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


Let x represent the width of the margin. Then the height of the printed area has to be 20 - 2x and the width has to be 16 - 2x. The x is multiplied by 2 because there is a margin on the top and another on the bottom, each of width x. Left and right, same thing. The area covered must be , so:



Apply FOIL



Put in standard form



Divide by common factor



Factor



Apply Zero Product Rule

or

But before you go off willy-nilly and submit both of those answers, let's think about this. If the page is only wide to begin with, how could the margin on each side be ? Extraneous root -- exclude it and go with the more reasonable (and correct) .

John