Would you guide me differentiating this integral for $m$:
$$\frac{\text{d}}{\text{d}m} \int_{x=-\infty}^m\int_{y=n}^{+\infty}\exp\left(-\left[\left(\frac{x-a}{b}\right)^2 - \frac{(x-a)(y-a)}{a}+\left(\frac{y-a}{c}\right)^2\right]\right)\space\text{d}y\text{d}x$$
noting that $a , b >0$

Ian say that $\frac{d}{dx} \int_a^x f(u) du = f(x)$ whatever a fixed.
so $\frac{d}{dm} \int_{x=-\infty}^m\int_{y=n}^{+\infty}\exp\left(-\left[\left(\frac{x-a}{b}\right)^2 - \frac{(x-a)(y-a)}{a}+\left(\frac{y-a}{c}\right)^2\right]\right)\space dy dx=\int_n^{\infty}\exp\left(-\left[\left(\frac{m-a}{b}\right)^2 - \frac{(m-a)(y-a)}{a}+\left(\frac{y-a}{c}\right)^2\right]\right)\space dy$.