[tex]\bf \lim\limits_{a\to b} \cfrac{a^2-3ab+2b^2}{a-b}\implies \lim\limits_{a\to b} \cfrac{(a-1b)(a-2b)}{a-b}
\\\\\\
\lim\limits_{a\to b} \cfrac{\underline{(a-b)}(a-2b)}{\underline{a-b}}
\implies
\lim\limits_{a\to b} a-2b\implies \lim\limits_{a\to b} b-2b\implies \lim\limits_{a\to b}-b[/tex]