document.write( "Question 1001695: find the domain of the function.\r
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\n" ); document.write( "\n" ); document.write( "f(x)= ln(x^2-9 / x^2+9x+14)
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Algebra.Com's Answer #618778 by ikleyn(52803)\"\" \"About 
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\n" ); document.write( "You need to determine where the function under the logarithm, \r
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\n" ); document.write( "\n" ); document.write( "f(x) = \"%28x%5E2-9%29%2F%28x%5E2+%2B+9x+%2B+14%29\"  is greater than zero,  f(x) > 0.\r
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\n" ); document.write( "\n" ); document.write( "Notice that  1)  \"x%5E2-9%29=\" = (x+3)*(x-3),  and  2)  \"x%5E2+%2B+9x+%2B+14\" = (x+2)*(x+7).     Therefore, \r
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\n" ); document.write( "\n" ); document.write( "f(x) = \"%28%28x%2B3%29%2A%28x-3%29%29%2F%28%28x%2B7%29%2A%28x%2B2%29%29\".\r
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\n" ); document.write( "\n" ); document.write( "Now,  f(x) > 0 \r
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\n" ); document.write( "\n" ); document.write( "1)  in the semi-infinite interval  x < -7,  or  (\"-infinity\", \"-7\");\r
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\n" ); document.write( "\n" ); document.write( "2)  in the interval  -3 < x < -2,  or  (-3, -2);\r
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\n" ); document.write( "\n" ); document.write( "3)  in the semi-infinite interval  x > 3,  or  (\"3\", \"infinity\").\r
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\n" ); document.write( "\n" ); document.write( "See the plots below.\r
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\n" ); document.write( "\n" ); document.write( "Figure. Plot f(x) (red line);
\n" ); document.write( "plot of the numerator (green line);
\n" ); document.write( "plot of denominator (blue line).\r
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