document.write( "Question 1045390: A number added to thrice its reciprocal is equal to 13/2. what is the number? \n" ); document.write( "
Algebra.Com's Answer #660819 by KMST(5328)\"\" \"About 
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There is nothing that says that the number is a positive integer,
\n" ); document.write( "but if that had been meant,the fifth grader approach would work well.
\n" ); document.write( "Otherwise, we could use the algebra approach.
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\n" ); document.write( "THE FIFTH GRADER APPROACH:
\n" ); document.write( "It cannot be a very small number, like \"1\" ,
\n" ); document.write( "because the sum would be too low.
\n" ); document.write( "It cannot be \"7\" or more,
\n" ); document.write( "because the sum would be more than \"7=14%2F2%3E13%2F2\" .
\n" ); document.write( "It must be a multiple of \"2\" ,
\n" ); document.write( "because the sum has a \"2\" in the denominator.
\n" ); document.write( "Could the number be \"4\" ?
\n" ); document.write( "Its reciprocal is \"1%2F4\" , and the sum i
\n" ); document.write( "\"4%2B3%281%2F4%29=4%2B3%2F4=16%2F4%2B3%2F4=19%2F4\" .
\n" ); document.write( "That is not \"13%2F2=26%2F4\" .
\n" ); document.write( "The sum is less than \"13%2F2\" ,
\n" ); document.write( "and obviously the bigger the starting number,
\n" ); document.write( "the larger the sum will be,
\n" ); document.write( "so let's try \"6\" .
\n" ); document.write( "The reciprocal of \"6\" is 1\"1%2F6\" ,
\n" ); document.write( "and the sum of \"6\" plus thrice its reciprocal is
\n" ); document.write( "\"6%2B3%281%2F6%29=6%2B3%2F6=6%2B1%2F2=12%2F2%2B1%2F2=13%2F2\" .
\n" ); document.write( "So, the number is \"highlight%286%29\" .
\n" ); document.write( "
\n" ); document.write( "THE ALGEBRA APPROACH:
\n" ); document.write( "\"x\" = the mystery number, and
\n" ); document.write( "\"1%2Fx\" = its reciprocal, so we know that \"x%3C%3E0\" .
\n" ); document.write( "Then,
\n" ); document.write( "\"x%2B3%281%2Fx%29\" = the mystery number added to thrice its reciprocal.
\n" ); document.write( "The problem say that sum is \"13%2F2\" , so our equation is
\n" ); document.write( "\"x%2B3%281%2Fx%29=13%2F2\" .
\n" ); document.write( "Solving:
\n" ); document.write( "1\"x%2B3%281%2Fx%29=13%2F2\"
\n" ); document.write( "\"x%2B3%2Fx=13%2F2\"
\n" ); document.write( "We multiply both sides of the equal sign in that equation times \"2x\" .
\n" ); document.write( "Since we now that \"x%3C%3E0\" , we know we get an equivalent equation.
\n" ); document.write( "\"%28x%2B3%2Fx%29%2A2x%29=%2813%2F2%29%2A2x\"
\n" ); document.write( "\"2x%5E2%2B%283%2Fx%29%2A2x=13x\"
\n" ); document.write( "\"2x%5E2%2B6=13x\"
\n" ); document.write( "\"2x%5E2-13x%2B6=0\"
\n" ); document.write( "We can solve that equation by factoring,
\n" ); document.write( "by completing the square,
\n" ); document.write( "or by using the quadratic formula,
\n" ); document.write( "to get the solutions
\n" ); document.write( "\"x=1%2F2\" and \"x=6\" .
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