document.write( "Question 161482: CAN SOMEONE PLEASE HELP ME WITH THIS PROBLEM PLEASE:\r
\n" ); document.write( "\n" ); document.write( "Find the domain of the composite function f o g.\r
\n" ); document.write( "\n" ); document.write( "f(x) = 2 / x + 10 , g(x) = 60 / x
\n" ); document.write( "

Algebra.Com's Answer #118993 by gonzo(654)\"\" \"About 
You can put this solution on YOUR website!
f(x) = 2/x + 10
\n" ); document.write( "i'll assume that means (2/x) + 10.
\n" ); document.write( "hopefully that's right.
\n" ); document.write( "if not, resubmit the question.
\n" ); document.write( "g(x) = 60/x.
\n" ); document.write( "-----
\n" ); document.write( "i assume you are looking for f(g(x)).
\n" ); document.write( "if that's what fog means then we're ok.
\n" ); document.write( "i'll answer for that.
\n" ); document.write( "resubmit the question if i got it wrong.
\n" ); document.write( "-----
\n" ); document.write( "g(x) = 60/x (given)
\n" ); document.write( "f(x) = (2/x) + 10 (given)
\n" ); document.write( "to solve for f(g(x)) you have to replace x with g(x).
\n" ); document.write( "this is no different then solving for f(3).
\n" ); document.write( "you replace x with 3.
\n" ); document.write( "-----
\n" ); document.write( "in this case you replace x with g(x) which means you replace
\n" ); document.write( "x with (60/x)
\n" ); document.write( "-----
\n" ); document.write( "since f(x) = (2/x) + 10, then
\n" ); document.write( "\"f%28g%28x%29%29+=+f%28%2860%2Fx%29%29+=+%28%282%29%2F%2860%2Fx%29%29+%2B+10\"
\n" ); document.write( "2/(60/x) is the same as (2*x)/60.
\n" ); document.write( "you get that by multiplying the numerator and denominator by x.
\n" ); document.write( "2*x/(60*x/x) = 2*x/60 since the x in the denominator cancels out.
\n" ); document.write( "equation becomes
\n" ); document.write( "\"f%28g%28x%29%29+=+f%28%2860%2Fx%29%29+=+%282%2Ax%2F%2860%29%29+%2B+10\"
\n" ); document.write( "this becomes
\n" ); document.write( "\"f%28g%28x%29%29+=+f%28%2860%2Fx%29%29+=+%28x%2F30%29+%2B+10\"
\n" ); document.write( "-----
\n" ); document.write( "the domain of f(x) would be all values of x except 0 since you can't divide by 0.
\n" ); document.write( "-----
\n" ); document.write( "the domain of g(x) would be the same, i.e. all values of x except 0 for the same reason.
\n" ); document.write( "-----
\n" ); document.write( "the domain of f(g(x)), however, would be all values of x since x is now in the numerator rather than the denominator.
\n" ); document.write( "
\n" ); document.write( "
\n" );