document.write( "Question 650517: The sum of eight consecutive even integers; n = first integer of the eight
\n" );
document.write( " \n" );
document.write( "
Algebra.Com's Answer #407327 by swincher4391(1107)![]() ![]() You can put this solution on YOUR website! Let n be the first; (n+2) be the second...\r \n" ); document.write( "\n" ); document.write( "Notice that for each kth even number, we can write it as (n+2(k-1)). This is unnecessary to solve the problem, but it may help you see where I come up with this next step:\r \n" ); document.write( "\n" ); document.write( "So continuing on, the 8th must be (n+14)\r \n" ); document.write( "\n" ); document.write( "So we have n+(n+2)+(n+4)+(n+6)+(n+8)+(n+10)+(n+12)+(n+14)\r \n" ); document.write( "\n" ); document.write( "=8n + 2*(sum of 1 to 7) \n" ); document.write( "=8n + 2*(28) \n" ); document.write( "=8n+56 \n" ); document.write( "=8(n+7) \n" ); document.write( "------------- \n" ); document.write( "Aside: \n" ); document.write( "Curiously, what if it was the first 9 even numbers?\r \n" ); document.write( "\n" ); document.write( "Then we'd have an added on (n+16).\r \n" ); document.write( "\n" ); document.write( "This would be 9n + 2*(sum of 1 to 8) \n" ); document.write( "= 9n + 2*(36) \n" ); document.write( "= 9n + 72 \n" ); document.write( "= 9(n+8)\r \n" ); document.write( "\n" ); document.write( "So, in general, the sum of k consecutive integers \n" ); document.write( "= k(n+(k-1)) \n" ); document.write( " \n" ); document.write( " |