document.write( "Question 1065945: The height of waves in a storm depends on the speed of the wind. Assuming the wind has no obstructions for a long distance, suppose the maximum wave height H for a wind speed x can be approximated by H = 0.02x^2+0.8x−17, where H is in feet and x is in knots (nautical miles per hour). For what wind speed would the maximum wave height be 7 ft? \n" ); document.write( "

Algebra.Com's Answer #681127 by stanbon(75887) $\"\"$ $\"About$

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The height of waves in a storm depends on the speed of the wind. Assuming the wind has no obstructions for a long distance, suppose the maximum wave height H for a wind speed x can be approximated by H = 0.02x^2+0.8x−17, where H is in feet and x is in knots (nautical miles per hour). For what wind speed would the maximum wave height be 7 ft?
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\n" ); document.write( "H(x) = 0.02x^2+0.8x−17
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\n" ); document.write( "Solve:: 0.02x^2 + 0.8x - 17 = 7
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\n" ); document.write( "0.02x^2 + 0.8x - 24 = 0
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\n" ); document.write( "2x^2 + 80x - 2400 = 0
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\n" ); document.write( "x^2 + 40x - 1200 = 0
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\n" ); document.write( "(x-20)(x+60) = 0
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\n" ); document.write( "Positive solution::
\n" ); document.write( "x = 20 knots/hr
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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