document.write( "Question 690565: the width of a rectangle is 8 feet less than the length. The area is 128square feet. what is the length and width \n" ); document.write( "
Algebra.Com's Answer #426333 by Stitch(470)\"\" \"About 
You can put this solution on YOUR website!
Set-Up
\n" ); document.write( "-------
\n" ); document.write( "A = L * W (Area of a rectangle)
\n" ); document.write( "Given: A = 128, L = W + 8
\n" ); document.write( "---------
\n" ); document.write( "Solution:
\n" ); document.write( "---------
\n" ); document.write( "Substitute the given information into the equation for the area of a rectangle
\n" ); document.write( "\"%28128%29+=+%28W+%2B+8%29+%2A+W\" Simplify
\n" ); document.write( "\"128+=+W%5E2+%2B+8W\" Subtract 128 from both sides
\n" ); document.write( "\"0+=+W%5E2+%2B+8W+-+128\"
\n" ); document.write( "Use the quadratic equation\r
\n" ); document.write( "\n" ); document.write( "\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation \"aW%5E2%2BbW%2Bc=0\" (in our case \"1W%5E2%2B8W%2B-128+=+0\") has the following solutons:
\n" ); document.write( "
\n" ); document.write( " \"W%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca\"
\n" ); document.write( "
\n" ); document.write( " For these solutions to exist, the discriminant \"b%5E2-4ac\" should not be a negative number.
\n" ); document.write( "
\n" ); document.write( " First, we need to compute the discriminant \"b%5E2-4ac\": \"b%5E2-4ac=%288%29%5E2-4%2A1%2A-128=576\".
\n" ); document.write( "
\n" ); document.write( " Discriminant d=576 is greater than zero. That means that there are two solutions: \"+x%5B12%5D+=+%28-8%2B-sqrt%28+576+%29%29%2F2%5Ca\".
\n" ); document.write( "
\n" ); document.write( " \"W%5B1%5D+=+%28-%288%29%2Bsqrt%28+576+%29%29%2F2%5C1+=+8\"
\n" ); document.write( " \"W%5B2%5D+=+%28-%288%29-sqrt%28+576+%29%29%2F2%5C1+=+-16\"
\n" ); document.write( "
\n" ); document.write( " Quadratic expression \"1W%5E2%2B8W%2B-128\" can be factored:
\n" ); document.write( " \"1W%5E2%2B8W%2B-128+=+1%28W-8%29%2A%28W--16%29\"
\n" ); document.write( " Again, the answer is: 8, -16.\n" ); document.write( "Here's your graph:
\n" ); document.write( "\"graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B8%2Ax%2B-128+%29\"

\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "The answers were W = 8feet or -16feet. but since you can not have a negative width. Just use the 8\r
\n" ); document.write( "\n" ); document.write( "Now we can find the length
\n" ); document.write( "L =W + 8
\n" ); document.write( "Plug 8 in for W
\n" ); document.write( "\"L+=+8+%2B%288%29\"
\n" ); document.write( "\"highlight_green%28L+=+16+feet%29\"\r
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "
\n" );