document.write( "Question 131842This question is from textbook College Algebra
\n" ); document.write( ": Directions: Find a polynomial of minimum degree (there are many) that have the given zeros: 1-sqrt(13), 1+sqrt(13). \r
\n" ); document.write( "\n" ); document.write( "I understand that if the zeros are: -2,0,2 then the polynomial would work out like this: x(x+2)(x-2)=x(x^2-4)=x^3-4x\r
\n" ); document.write( "\n" ); document.write( "But the whole square root thing is really throwing me off, if you could help, I would really appreciate it. Thank you for your time. :o)
\n" ); document.write( "

Algebra.Com's Answer #96268 by solver91311(24713)\"\" \"About 
You can put this solution on YOUR website!
You have it right. Just look at your zeros, \"1-sqrt%2813%29\" and \"1%2Bsqrt%2813%29\" as if they were just numbers (which they are actually), and do what you would do with a number.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "a is a root of the polynomial equation if and only if \"x-a\" is a factor of the polynomial, so for your problem the factors are:\r
\n" ); document.write( "\n" ); document.write( "\"x-%281-sqrt%2813%29%29\" and \"x-%281%2Bsqrt%2813%29%29\", so:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"y=%28x-1%2Bsqrt%2813%29%29%28x-1-sqrt%2813%29%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now you have to extend the FOIL process somewhat to multiply what are actually trinomials, but if you follow a pattern, it will all work out.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"y=x%5E2-x-x%2Asqrt%2813%29-x%2B1%2Bsqrt%2813%29%2Bx%2Asqrt%2813%29-sqrt%2813%29-13\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now collect terms:
\n" ); document.write( "\"y=x%5E2-2x-12\". Done.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "To check the answer, you can complete the square on the resultant polynomial:
\n" ); document.write( "Set the polynomial equal to 0:
\n" ); document.write( "\"x%5E2-2x-12=0\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Put the constant on the right:
\n" ); document.write( "\"x%5E2-2x=12\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Divide the first degree term coefficient by 2 and square the result, adding the result to both sides:
\n" ); document.write( "\"x%5E2-2x%2B1=13\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"%28x-1%29%5E2=13\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x-1=sqrt%2813%29\" or \"x-1=-sqrt%2813%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=1%2Bsqrt%2813%29\" or \"x=1-sqrt%2813%29\". Answer checks.
\n" ); document.write( "
\n" );