document.write( "Question 118450: Hello, I need some help on finding the value of c that makes each trinomial a perfect square. The problem is;
\n" ); document.write( "[n^2+14n+c]
\n" ); document.write( "I have tried the formula: [(a+b)^2=a^2+2ab+b^2]
\n" ); document.write( "But I seem to be getting stuck trying to find the value of [b]\r
\n" ); document.write( "\n" ); document.write( "May someone show me how to work out the problem?
\n" ); document.write( "Thank you :]
\n" ); document.write( "

Algebra.Com's Answer #86566 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
Since we're trying to make \"n%5E2%2B14n%2Bc\" a perfect square, this means \"%28a%2Bb%29%5E2=n%5E2%2B14n%2Bc\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"a%5E2%2B2ab%2Bb%5E2=n%5E2%2B14n%2Bc\" Foil \"%28a%2Bb%29%5E2\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Since we know that the first term on the right is \"n%5E2\", this means \"a%5E2=n%5E2\" which tells us that \"a=n\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"n%5E2%2B2nb%2Bb%5E2=n%5E2%2B14n%2Bc\" Plug in \"a=n\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So this means that \"2nb=14n\" (notice how both of these terms only have 1 \"n\") and \"b%5E2=c\" (notice how both of these terms have no \"n\" terms)\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So let's use \"2nb=14n\" to solve for b\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"2nb=14n\" Start with the given equation\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"cross%282n%2F2n%29b=14n%2F2n\" Divide both sides by 2n to isolate b\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"b=7\" Divide \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"n%5E2%2B14n%2B7%5E2\" Now plug in \"b=7\" into the original polynomial \"n%5E2%2B14n%2Bc\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"n%5E2%2B14n%2B49\" Now square 7 to get 49\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So this means that the perfect square is \"n%5E2%2B14n%2B49\" \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Check:\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Notice how if we factor \"n%5E2%2B14n%2B49\" we get \"%28n%2B7%29%5E2\" which shows us that \"n%5E2%2B14n%2B49\" is a perfect square. So our answer is verified.
\n" ); document.write( "
\n" );