document.write( "Question 985848: Help pls 😊
\n" ); document.write( "Triangular numbers are: 1,3,6,10....where the nth such number is n(n-1)/2. Show that the sum of two consecutive triangular numbers is a square number.
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Algebra.Com's Answer #606671 by Alan3354(69443)\"\" \"About 
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Triangular numbers are: 1,3,6,10....where the nth such number is n(n-1)/2. Show that the sum of two consecutive triangular numbers is a square number.
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\n" ); document.write( "n(n-1)/2 + (n+1)*n/2 = (n^2-n + n^2+n)/2
\n" ); document.write( "= 2n^2/2
\n" ); document.write( "= n^2
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