document.write( "Question 193570: Can you please help me with the following problem:\r
\n" ); document.write( "\n" ); document.write( "Find the domain of f(g(x)). F(x)= 4/(x-2) and g(x)=3/(x-5)\r
\n" ); document.write( "\n" ); document.write( "I know that the domain of f(x) is (-infinity,2)U (2,infinity) and g(x) is (-infinity,5)U (5,infinity)
\n" ); document.write( "I know that f(x) has got to be set to the number that the domain cannot use in g(x)
\n" ); document.write( "So that would be 5=4/(x-2)
\n" ); document.write( "Then multiply each side by (x-2). (x-2)(5)=(4/(x-2))(x-2) this cancel out the denominator.\r
\n" ); document.write( "\n" ); document.write( "Then the problem would be 5x-10=4, subtract 10 from each side to isolate the variable. 5x-10+10=4+10 => 5x=14. Then to isolate x, x would have to be divided by 5. 5x/5=14/5 => x=14/5\r
\n" ); document.write( "\n" ); document.write( "So would the domain be (-infinity,2)U(2,(14/5))U((14/5),5)U(5,infinity)?\r
\n" ); document.write( "\n" ); document.write( "please let me know if any mistakes were made\r
\n" ); document.write( "\n" ); document.write( "thanks!
\n" ); document.write( "
\n" ); document.write( "

Algebra.Com's Answer #145291 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
First, let's find the domain of g(x):\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"g%28x%29=3%2F%28x-5%29\" Start with the given function\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x-5=0\" Set the denominator equal to zero\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=5\" Add 5 to both sides. So plugging 5 into the denominator results in a division by zero. So we must take this value out of the domain.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So the domain of g(x) is: x can be any real number but \"x%3C%3E5\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "------------------------------------------------------------\r
\n" ); document.write( "\n" ); document.write( "Now let's find the domain of f(g(x))\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"f%28x%29=4%2F%28x-2%29\" Start with the given function\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"f%28x%29=4%2F%283%2F%28x-5%29-2%29\" Plug in \"g%28x%29=3%2F%28x-5%29\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"f%28x%29=%284%28x-5%29%29%2F%283-2%28x-5%29%29\" Multiply EVERY term by the inner LCD \"x-5\" to clear out the inner fractions.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"f%28x%29=%284x-20%29%2F%283-2x%2B10%29\" Distribute\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"f%28x%29=%284x-20%29%2F%28-2x%2B13%29\" Combine like terms.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"-2x%2B13=0\" Set the denominator equal to zero\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"-2x=0-13\" Subtract \"13\" from both sides.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"-2x=-13\" Combine like terms on the right side.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=%28-13%29%2F%28-2%29\" Divide both sides by \"-2\" to isolate \"x\".\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=13%2F2\" Reduce.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So we must take \"x=13%2F2\" out of the domain (since this value causes a division by zero)\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So the domain of f(g(x)) is: x can be any real number but \"x%3C%3E13%2F2\". In addition, we made a previous statement that \"x%3C%3E5\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So this means that the domain of f(g(x)) in interval notation is \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "
\n" );