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The length of a rectangle is 23 centimeters less than four times its width. Its area is 72 square centimeters. Find the dimensions of the rectangle The width is The length is

User Eric Bock
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1 Answer

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9 votes

Let the width be x

The lenght will be 4x-23

The area is lenghtX width, so:

x(4x-23) = 72

4x² -23x -72=0

Using the quadratic formula:


\begin{gathered} x=\frac{-b\pm\sqrt[\square]{b^(2)-4ac}}{2a} \\ x=\frac{23\pm\sqrt[\square]{529+1152_{}}}{8} \\ x=(23\pm41)/(8) \\ x1=8 \\ x2=-18/8 \end{gathered}

We'll use the value of x1, because we're looking for a measure, so it has to be positive.

Then, the width is 8cm. The lenght is 4*8-23= 9cm.

User TheBlastOne
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