$2.$ Consider the function f$($x$)=4x^2+3x$

$($a$)$ Find the deifference quotient $\frac{f(x+h)-f(x)}{h}$ for the function f$($x$)=4x^2+3x$ and simplify it

$($b$)$ Substitute x$=2$ and h$=-4$ into your simplified difference quotient from part $($a$)$ and explain the meaning of the value that results.