document.write( "Question 30097: When ace airlines changed to planes that flew 100 km/h faster than its old ones, the time of its 2800 km Dallas-Seattle flight was reduced by 30 minutes. Find the speed of the new planes\r
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\n" ); document.write( "\n" ); document.write( "Let the speed be x (orignal)
\n" ); document.write( "increased speed = x+100
\n" ); document.write( "30 minutes =0.5hours
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\n" ); document.write( "\n" ); document.write( "a=0.5, b=50, c=-280000\r
\n" ); document.write( "\n" ); document.write( "Simplfy and you get two solutions:
\n" ); document.write( "x=-800 and x=700
\n" ); document.write( "Remove the negavtive
\n" ); document.write( "x=700
\n" ); document.write( "700+100=800\r
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\n" ); document.write( "\n" ); document.write( "Hence, the speed of the new planes is 800km/h\r
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Algebra.Com's Answer #16834 by Paul(988)\"\" \"About 
You can put this solution on YOUR website!
Let the speed be x (orignal)
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document.write( "increased speed = x+100
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document.write( "30 minutes =0.5hours
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document.write( "Equation:
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document.write( "\"2800%28%28x%2B100%29-%28x%29%29=0.5%28%28x%29%28x%2B100%29%29\"\r
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document.write( "\"2800%28100%29=0.5%28x%5E2%2B100x%29\"
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document.write( "\"280000=0.5x%5E2%2B50x\"
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document.write( "\"0.5x%5E2%2B50x-280000=0\"\r
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document.write( "\"x=%28-b%2B-sqrt%28b%5E2-4%2Aa%2Ac%29%29%2F%282%2Aa%29\"
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document.write( "a=0.5, b=50, c=-280000
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document.write( "\"x=%28-50%2B-sqrt%2850%5E2-4%2A0.5%2A-280000%29%29%2F%282%2A0.5%29\"
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document.write( "Simplfy and you get two solutions:
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document.write( "x=-800 and x=700
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document.write( "Remove the negavtive
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document.write( "x=700
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document.write( "700+100=800\r
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document.write( "Hence, the speed of the new planes is 800km/h
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document.write( "Paul. \n" );
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