document.write( "Question 643417: two boats leave port at the same time, one east and one south (90 degree angle)
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document.write( "the eastbound boats speed is 2mph greater than the southbound boats speed. after 9 hours the boats are 90 miles apart. what is the southbound boats speed? \n" );
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Algebra.Com's Answer #404471 by lwsshak3(11628)![]() ![]() ![]() You can put this solution on YOUR website! two boats leave port at the same time, one east and one south (90 degree angle) \n" ); document.write( "the eastbound boats speed is 2mph greater than the southbound boats speed. after 9 hours the boats are 90 miles apart. what is the southbound boats speed? \n" ); document.write( "** \n" ); document.write( "let x=speed of southbound boat \n" ); document.write( "x+2=speed of eastbound boat \n" ); document.write( "After 9 hours: \n" ); document.write( "southbound boat traveled 9x miles \n" ); document.write( "eastbound boat traveled 9(x+2) miles \n" ); document.write( ".. \n" ); document.write( "draw a right triangle with legs 9x and 9(x+2) and hypotenuse=90 \n" ); document.write( "by pythagorean theorem: \n" ); document.write( "(9x)^2+[9(x+2)]^2=90^2 \n" ); document.write( "81x^2+81(x^2+4x+4)=8100 \n" ); document.write( "divide by 81 \n" ); document.write( "x^2+x^2+4x+4=100 \n" ); document.write( "2x^2+4x-96=0 \n" ); document.write( "divide by 2 \n" ); document.write( "x^2+2x-48=0 \n" ); document.write( "(x+8)(x-6)=0 \n" ); document.write( "x=-8 (reject,x>0) \n" ); document.write( "x=6 \n" ); document.write( "speed of southbound boat=6 mph \n" ); document.write( " \n" ); document.write( " |