ANSWER
[tex]f(x + h) = \frac{4x + 4h}{1 - x - h}[/tex]
EXPLANATION
The given expression is
[tex]f(x) = \frac{4x}{1 - x} [/tex]
To find an expression for f(x+h), we substitute x+h, wherever we see x in the given expression.
This implies that,
[tex]f(x + h) = \frac{4(x + h)}{1 - (x + h)} [/tex]
We simplify to obtain;
[tex]f(x + h) = \frac{4x + 4h}{1 - x - h} [/tex]
