P: 26

Okay, thanks.
But in this notation [itex]\int^{b}_{a}{f(x).dx}[/itex] I know it means area under the curve on interval [a,b] what if I take dx<0 how can I explain it? I mean I can take limit (lim [itex]\frac{Δy}{Δx}[/itex] as x approximates either side of xaxis (Δx→0[itex]^{+}[/itex] and Δx→0[itex]^{}[/itex]) I realize that if dx>0 or dx<0 at derivative of a function but I'm not sure about integral??
