document.write( "Question 311704: Hello!\r
\n" ); document.write( "\n" ); document.write( "I am currently in algebra 1 at my middle school and I am trying to study for finals. I am having some trouble with quadratic equations and I hope that you can help.\r
\n" ); document.write( "\n" ); document.write( "My teacher said to use the quadratic formula to find solutions and I have no idea how to do that.\r
\n" ); document.write( "\n" ); document.write( "Here is the problem:\r
\n" ); document.write( "\n" ); document.write( "(x-8)(x+1)=-20\r
\n" ); document.write( "\n" ); document.write( "Thank you very much for your time and effort.\r
\n" ); document.write( "\n" ); document.write( "Sincerely,
\n" ); document.write( " Lyn \n" ); document.write( "

Algebra.Com's Answer #222948 by Earlsdon(6294) $\"\"$ $\"About$

You can put this solution on YOUR website!
Solve:
\n" ); document.write( " $\"%28x-8%29%28x%2B1%29+=+-20\"$ First, multiply the two factors on the left side using the FOIL method.
\n" ); document.write( " $\"x%5E2%2Bx-8x-8+=+-20\"$ Simplify the left side.
\n" ); document.write( " $\"x%5E2-7x-8+=+-20\"$ Now add 20 to both sides to get the equation in standard form: $\"ax%5E2%2Bbx%2Bc+=+0\"$ .
\n" ); document.write( " $\"x%5E2-7x-8%2B20+=+0\"$ Simplify.
\n" ); document.write( " $\"x%5E2-7x%2B12+=+0\"$ Now you can apply the quadratic formula: $\"x+=+%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F2a\"$ and, in your equation, a = 1, b = -7, and c = 12, so make the appropriate substitutions:
\n" ); document.write( " $\"x+=+%28-%28-7%29%2B-sqrt%28%28-7%29%5E2-4%281%29%2812%29%29%29%2F2%281%29\"$ Simplify.
\n" ); document.write( " $\"x+=+%287%2B-sqrt%2849-48%29%29%2F2\"$
\n" ); document.write( " $\"x+=+%287%2B-sqrt%281%29%29%2F2\"$
\n" ); document.write( " $\"x+=+%287%2B1%29%2F2\"$ or $\"%287-1%29%2F2\"$
\n" ); document.write( " $\"highlight%28x+=+4%29\"$ or $\"highlight%28x+=+3%29\"$ \n" ); document.write( "

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