Tìm các giới hạn :
1, lim \frac{1}{(x-1)^2}.\frac{2x+3}{2x-3} 2,\mathop {\lim }\limits_{x \to 1}\frac{5}{(x-1)(x^2-3x+2)}
3, \mathop {\lim }\limits_{x \to 1} (\frac{1}{x}- \frac{1}{3})\frac{1}{(x-3)^3} 4, \mathop {\lim }\limits_{x \to (-2)^{+}}\frac{4x^4+3}{2x^2+3x-2}
5, \mathop {\lim }\limits_{x \to 2}\frac{\left| {2-x} \right|}{(x-2)^2} 6, \mathop {\lim }\limits_{x \to 0}\frac{x^2-3}{x^3+x^2}