document.write( "Question 1133242: What is the smallest positive integer which is 2 times the square of some
\n" ); document.write( "positive integer and also 5 times the fifth power of some other positive integer?
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Algebra.Com's Answer #750488 by greenestamps(13200)\"\" \"About 
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\n" ); document.write( "We are looking for the smallest positive integer that is both 2 times the square of some positive integer and 5 times the 5th power of another positive integer:

\n" ); document.write( "\"2x%5E2+=+5y%5E5\"

\n" ); document.write( "There is a single known factor of 2 on the left and a single known factor of 5 on the right. That means both x and y must both contain factors of only 2 and/or 5. So

\n" ); document.write( "let \"x%5E2+=+%282%5Ea%29%285%5Eb%29\", where a and b are even; and
\n" ); document.write( "and \"y%5E5+=+%282%5Ec%29%285%5Ed%29\", where c and d are multiples of 5

\n" ); document.write( "Then

\n" ); document.write( "\"2%2A%282%5Ea%29%285%5Eb%29+=+5%282%5Ec%29%285%5Ed%29\"

\n" ); document.write( "\"%282%5E%28a%2B1%29%29%285%5Eb%29+=+%285%5E%28d%2B1%29%29%282%5Ec%29\"

\n" ); document.write( "From that we know

\n" ); document.write( "\"c+=+a%2B1\" and \"b+=+d%2B1\"

\n" ); document.write( "For the smallest positive integer for which all those are true, we need to have c = d = 5; that makes a=4 and b=6.

\n" ); document.write( "And we finally have

\n" ); document.write( "\"x%5E2+=+%282%5E4%29%285%5E6%29\" --> \"2x%5E2+=+%282%5E5%29%285%5E6%29\"
\n" ); document.write( "\"y%5E5+=+%282%5E5%29%285%5E5%29\" --> \"5y%5E2+=+%282%5E5%29%285%5E6%29\"

\n" ); document.write( "So the smallest positive integer that is both 2 times the square of one positive integer and 5 times the 5th power of another positive integer is

\n" ); document.write( "\"%282%5E5%29%285%5E6%29+=+500000\"

\n" ); document.write( "\"500000+=+2%28250000%29+=+2%28500%5E2%29+=+2x%5E2\"
\n" ); document.write( "\"500000+=+5%28100000%29+=+5%2810%5E5%29+=+5y%5E5\"
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