A, S, M and D are functions of $x$ and $y$, and they are defined as follows:
$A(x, y) = x + y$
$S(x, y) = x - y$
$M(x, y) = xy$
$D(x, y) = \dfrac{x}{y}, \quad y \neq 0$
If the domain of the function \[ f(x)=\log\left(10x^2-17x+7\right)\left(18x^2-11x+1\right) \] is $(-\infty,a)\cup(b,c)\cup(d,\infty)-\{e\}$, then $90(a+b+c+d+e)$ equals
For any natural number $k$, let $a_k = 3^k$. The smallest natural number $m$ for which \[ (a_1)^1 \times (a_2)^2 \times \dots \times (a_{20})^{20} \;<\; a_{21} \times a_{22} \times \dots \times a_{20+m} \] is: