SOLUTION: a rectangular photograph has an area of 40 inches. If the width of the photograph is 3 inches less than its height, find the dimensions of the photograph

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Question 1109313: a rectangular photograph has an area of 40 inches. If the width of the photograph is 3 inches less than its height, find the dimensions of the photograph
Answer by ikleyn(52775) About Me  (Show Source):
You can put this solution on YOUR website!
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1. Mental solution. 

     8 x 5 inches.

2. Algebra solution. 

    The condition gives you this equation

        x*(x+3) = 40.

        x^2 + 3x - 40 = 0.

    Now apply the quadratic formula or solve equation by factoring.


    On quadratic formula see the lessons

        Introduction into Quadratic Equations

        PROOF of quadratic formula by completing the square

    in this site.