document.write( "Question 1020225: If x and y are real, x^4y^5+x^5y^4 = 810 & x^6y^3+x^3y^6 = 945, Find 2x^3+(xy)^3+2y^3 = ? \n" ); document.write( "
Algebra.Com's Answer #636162 by robertb(5830)\"\" \"About 
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\"x%5E4y%5E5%2Bx%5E5y%5E4+=+810+\"==>\"x%5E3y%5E3%28x%5E2y%2Bxy%5E2%29+=+810\" after factoring \"x%5E3y%5E3\" and changing the order of the terms.\r
\n" ); document.write( "\n" ); document.write( "==> \"x%5E3y%5E3%283x%5E2y%2B3xy%5E2%29+=+2430\" (Equation A)\r
\n" ); document.write( "\n" ); document.write( "after multiplying both sides by 3.\r
\n" ); document.write( "\n" ); document.write( "Similarly, factor out \"x%5E3y%5E3\" from the 2nd equation \"x%5E6y%5E3%2Bx%5E3y%5E6+=+945\":\r
\n" ); document.write( "\n" ); document.write( "\"x%5E3y%5E3%28x%5E3+%2B+y%5E3%29+=+945\" (Equation B)\r
\n" ); document.write( "\n" ); document.write( "Add corresponding sides of Eqn. A and Eqn. B, to get\r
\n" ); document.write( "\n" ); document.write( "\"x%5E3y%5E3%28x%5E3+%2B+3x%5E2y%2B3xy%5E2%2B+y%5E3%29+=+3375\"
\n" ); document.write( "==>\"x%5E3y%5E3%28x%2By%29%5E3+=+3375\"
\n" ); document.write( "==> xy(x+y) = 15, (Equation C)
\n" ); document.write( "after taking cube roots of both sides.\r
\n" ); document.write( "\n" ); document.write( "Now the first equation \"x%5E4y%5E5%2Bx%5E5y%5E4+=+810+\" is the same as
\n" ); document.write( "\"x%5E4y%5E4%28x%2By%29+=+810\" (Equation D)
\n" ); document.write( "Dividing Eqn.D by Eqn.C, we get\r
\n" ); document.write( "\n" ); document.write( "\"x%5E3y%5E3+=+810%2F15+=54\"
\n" ); document.write( "Hence, \"+%28xy%29%5E3=54\" (Equation E) \r
\n" ); document.write( "\n" ); document.write( "Putting \"x%5E3y%5E3+=+54\" into Eqn.B, we get
\n" ); document.write( "\"54%28x%5E3%2By%5E3%29+=+945\" ==> \"x%5E3%2By%5E3+=+35%2F2\", or
\n" ); document.write( "\"2x%5E3%2B2y%5E3+=+35\" (Equation F)\r
\n" ); document.write( "\n" ); document.write( "Finally, combining Equations E and F, we get \r
\n" ); document.write( "\n" ); document.write( "\"2x%5E3%2B%28xy%29%5E3%2B2y%5E3+=+35%2B54+=+highlight%2889%29\".\r
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