document.write( "Question 685731: f(x)= x^2-4x
\n" ); document.write( "find f^-1(x) \n" ); document.write( "

Algebra.Com's Answer #424547 by stanbon(75887) $\"\"$ $\"About$

You can put this solution on YOUR website!
f(x)= x^2-4x
\n" ); document.write( "find f^-1(x)
\n" ); document.write( "----
\n" ); document.write( "1st: Interchange x and y to get:
\n" ); document.write( "x = y^2-4y
\n" ); document.write( "----
\n" ); document.write( "2nd: Solve for \"y\":
\n" ); document.write( "y^2-4y-x = 0
\n" ); document.write( "----
\n" ); document.write( "y = [4 +- sqrt(16-4*-x)]/2
\n" ); document.write( "--
\n" ); document.write( "y = [4 +- sqrt(16+4x)]/2
\n" ); document.write( "---
\n" ); document.write( "f^-1(x) = [4 + sqrt(16+4x)]/2 or f^-1(x) = [4 - sqrt(16+4x)]/2
\n" ); document.write( "====================
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "

\n" );