document.write( "Question 132237: Domain of the function
\n" ); document.write( "15/x^2-400 \n" ); document.write( "
Algebra.Com's Answer #96607 by nycsharkman(136)\"\" \"About 
You can put this solution on YOUR website!
The domain is the value(s) that we can replace x with safely.\r
\n" ); document.write( "\n" ); document.write( "Your function is\r
\n" ); document.write( "\n" ); document.write( "15/(x^2 - 400)\r
\n" ); document.write( "\n" ); document.write( "Your denominator is clearly the difference of two perfect squares.\r
\n" ); document.write( "\n" ); document.write( "Your denominator becomes the following two factors: (x - 20) (x + 20).\r
\n" ); document.write( "\n" ); document.write( "We set each factor to = 0 and solve for x.\r
\n" ); document.write( "\n" ); document.write( "x - 20 = 0\r
\n" ); document.write( "\n" ); document.write( "x = 20\r
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\n" ); document.write( "\n" ); document.write( "x + 20 = 0\r
\n" ); document.write( "\n" ); document.write( "x = -20\r
\n" ); document.write( "\n" ); document.write( "What is the domain?\r
\n" ); document.write( "\n" ); document.write( "The domain will be ALL REAL NUMBERS EXCEPT x = -20 and x = 20?\r
\n" ); document.write( "\n" ); document.write( "WHY?\r
\n" ); document.write( "\n" ); document.write( "If you replace x with -20 and 20 in the original function, you get a ZERO in the denominator of your fraction. Division by ZERO is NOT allowed in the world of math.\r
\n" ); document.write( "\n" ); document.write( "That is the reason why x CANNOT be -20 or 20 for this function.\r
\n" ); document.write( "\n" ); document.write( "Final answer: The domain is ALL REAL NUMBERS EXCEPT x = -20 and x = 20?\r
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