document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=639002>Question 639002</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please help me solve this equation: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x%5E2%2B8x-9+ ALIGN=MIDDLE  ALT=\"+x%5E2%2B8x-9+\"   DISABLED_style= \"max-width:90%; height:auto;\" >                             this is factor completely </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #402537 by </B><A HREF=/tutors/aboutme.mpl?userid=tam144><B>tam144(6)</B></A><img src=\"/images/stars/stars-05.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=tam144><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=402537\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Solve x^2 + 8x - 9 = 0. <BR>\n" );
document.write( "There are 2 Tips you should know when you meet this special type of quadratic equation. The standard form of a quadratic equation is: ax^2 + bx + c = 0.\r<BR>\n" );
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document.write( "Tip 1. When a + b + c = 0, one real root is x1 = 1 and the other x2 = c/a.<BR>\n" );
document.write( "Example 1. Solve x^2 + 8x - 9 = 0. You see that a + b + c = 1 + 8 - 9 = 0. This is Tip 1. One real root is x1 = 1 and the other x2 = c/a = -9/1 = -9.<BR>\n" );
document.write( "Example 2. Solve 7x^2 - 15x + 8 = 0. You find 7 - 15 + 8 = 0. This is Tip 1. The 2 real roots are: x1 = 1 and x2 = c/a = 8/7.\r<BR>\n" );
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document.write( "TIP 2. When a - b + c = 1, one real root x1 = -1 and the other x2 = -c/a.<BR>\n" );
document.write( "Example 3. Solve 3x^2 - 5x - 8 = 0. You find 3 -(-5) - 8 = 0. This is Tip 2. Then one real root x1 = -1 and the other x2 = -c/a = 8/1 = 8.<BR>\n" );
document.write( "Example 4. Solve 5x^2 + 17x + 12 = 0 . You find 5 -(17) + 12 = 0. Then x1 = -1 and x2 = -c/a = -12/5.\r<BR>\n" );
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document.write( "I advise you to remember these 2 Tips. It will save you a lot of time in solving quadratic equations.\r<BR>\n" );
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document.write( "Or, you can solve the given equation x^2 + 8x - 9 = 0 by the popular factoring method. Find 2 numbers whose product is -9 and whose sum is 8. Proceed: (-1, 9),(1, -9)OK. Factor the equation: x^2 + 8x - 9 = (x - 1)(x + 9) = 0.<BR>\n" );
document.write( "Next, solve the 2 binomials for x. <BR>\n" );
document.write( "x - 1 = 0  --> x = 1 and (x + 9) = 0  --> x = -9. </SPAN>\n" );
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