document.write( "Question 45922: Hi again,\r
\n" ); document.write( "\n" ); document.write( "This type of problem is still giving me some trouble:\r
\n" ); document.write( "\n" ); document.write( "The sum of the squares of two numbers is 117. The difference of the squares of the same two numbers is 45. Find the numbers. \r
\n" ); document.write( "\n" ); document.write( "Thanks again,
\n" ); document.write( "Louis
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Algebra.Com's Answer #30509 by abhijitvakil(7)\"\" \"About 
You can put this solution on YOUR website!
Hi Louis,\r
\n" ); document.write( "\n" ); document.write( "The solution isgiven in the problem itself. Always try to convert the statements of the problem into equations. Note -\r
\n" ); document.write( "\n" ); document.write( "Lets say the two numbers are x & y. Now as per the first statement, the sum of the squares of these numbers is 117. In mathematical language this would be written as:\r
\n" ); document.write( "\n" ); document.write( "\"x%5E2+%2B+y%5E2+=+117\"\r
\n" ); document.write( "\n" ); document.write( "Lets put this as eq. no. 1\r
\n" ); document.write( "\n" ); document.write( "The second condition is that the difference of the squares is 45, therefore it can be written as:\r
\n" ); document.write( "\n" ); document.write( "\"x%5E2+-+y%5E2+=+45\"\r
\n" ); document.write( "\n" ); document.write( "This gives us equation no. 2 ok ?
\n" ); document.write( "Now to solve a problem having two unknown quantities, we need atleast 2 sets of relations between them. Here we have the 2 relations as eq 1 & eq 2. Thus we may now proceed to solve them. In order to solve these equations, the approach is to manipulate them in such a manner that we are left with only one variable. Here if you simply add these two equations to each other, what we get is :\r
\n" ); document.write( "\n" ); document.write( "\"x%5E2+%2B+y%5E2+%2B+x%5E2+-+y%5E2+=+117+%2B+45\"\r
\n" ); document.write( "\n" ); document.write( "I hope this much is clear\r
\n" ); document.write( "\n" ); document.write( "Or\r
\n" ); document.write( "\n" ); document.write( "\"2x%5E2+=+162\"\r
\n" ); document.write( "\n" ); document.write( "or\r
\n" ); document.write( "\n" ); document.write( "\"x%5E2+=+81\" (divide both sides by 2)\r
\n" ); document.write( "\n" ); document.write( "Obviously x = 9.\r
\n" ); document.write( "\n" ); document.write( "Now put this value of x in eq 1, we get\r
\n" ); document.write( "\n" ); document.write( "\"9%5E2+%2B+y%5E2+=+117\"\r
\n" ); document.write( "\n" ); document.write( "or\r
\n" ); document.write( "\n" ); document.write( "\"81+%2B+y%5E2+=+117\"\r
\n" ); document.write( "\n" ); document.write( "or \r
\n" ); document.write( "\n" ); document.write( "\"y%5E2+=+117+-+81+=+36\"\r
\n" ); document.write( "\n" ); document.write( "Thus y = 6.\r
\n" ); document.write( "\n" ); document.write( "Hence we have the solution as x= 9, y = 6. Please note that i have given detailed explanations which are not required when you actually solve the problem in an exam. Enjoy solving
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