Solution
We have the following function given:
[tex]f(x)=\frac{1}{2x-9}[/tex]and we want to find:
[tex]\frac{f(x+h)-f(x)}{h}[/tex]Replacing we have:
[tex]\frac{\frac{1}{2(x+h)-9}-\frac{1}{2x-9}}{h}=\frac{\frac{2x-9-2x-2h+9}{(2(x+h)-9)(2x-9)}}{h}[/tex]And if we simplify we got:
[tex]\frac{-2h}{h\lbrack(2x+2h-9)(2x-9)\rbrack}=\frac{-2}{(2(x+h)-9)(2x-9)}[/tex]