document.write( "Question 1034616: Find the rules for the composite functions (g ◦ f)(x) and (f ◦ g)(x)
\n" ); document.write( "b) If f(x) = 4 − 4x + x^2 and g(x) = x^2/x − 4
\n" ); document.write( "

Algebra.Com's Answer #649270 by Theo(13342)\"\" \"About 
You can put this solution on YOUR website!
f(x) = \"%284-4x%2Bx%5E2%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "g(x) = \"%28x%5E2%2F%28x-4%29%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "fog(x) = f(g(x))\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "gof(x) = g(f(x))\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "i use the letter \"o\" to indicate the composition symbol.
\n" ); document.write( "it's easier than trying to figure out what the code for the composition symbol is.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "the argument in f(x) is equal to x.
\n" ); document.write( "the argument in f(g(x)) is equal to g(x).
\n" ); document.write( "in order to find fog(x), you need to replace the argument of x with the argument of g(x).
\n" ); document.write( "since g(x) = \"%28x%5E2%2F%28x-4%29%29\", you need to replace x in f(x) with \"%28x%5E2%2F%28x-4%29%29\".\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "you will get:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "f(x) = \"%284-4x%2Bx%5E2%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "f(g(x)) = \"%284-4%2Ag%28x%29%2Bg%28x%29%5E2%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "since g(x) = \"%28x%5E2%2F%28x-4%29%29\", then .....\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "f(g(x)) = \"%284-4%2A%28x%5E2%2F%28x-4%29%29%2B%28x%5E2%2F%28x-4%29%29%5E2%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "likewise, .....
\n" ); document.write( "the argument in g(x) is x.
\n" ); document.write( "the argument in g(f(x)) is f(x).
\n" ); document.write( "in order to find gof(x), you need to replace the argument of x with the argument of f(x).
\n" ); document.write( "since f(x) = \"%284-4x%2Bx%5E2%29\", you need to replace x in g(x) with \"%284-4x%2Bx%5E2%29\".\r
\n" ); document.write( "\n" ); document.write( "you will get:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "g(x) = \"%28x%5E2%2F%28x-4%29%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "g(f(x)) = \"%28f%28x%29%5E2%2F%28f%28x%29-4%29%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "since f(x) = \"%284-4x%2Bx%5E2%29\", then .....\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "g(f(x)) = \"%28%284-4x%2Bx%5E2%29%5E2%2F%28%284-4x%2Bx%5E2%29-4%29%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "
\n" );