Question 277467
4x/x+1 = ?/(x+1)(x-1)
:
Replace ? with y
{{{4x/(x+1) = y/((x+1)(x-1))}}} 
Cross multiply
y(x+1) = 4x(x+1)(x-1)
:
Divide by (x+1)
y = {{{(4x(x+1)(x-1))/(x+1)}}}
:
Cancel (x+1)
y = 4x(x-1)
:
Replacing the ?
{{{4x/(x+1)}}} = {{{(4x(x-1))/((x+1)(x-1))}}}