$\displaystyle \lim\limits _{x\rightarrow -1}\frac{x^{3} +3x+4}{2x^{2} -2} =?\ $ $\displaystyle \lim\limits _{x\rightarrow 1}\frac{x^{4} -x^{3} -x+1}{x^{3} -3x+2} =?\ $ $\displaystyle \lim\limits _{x\rightarrow 1}\frac{x^{3} -1}{x^{2} +x-2} =?\ $ $\displaystyle \lim\limits _{x\rightarrow 2}\frac{5x^{2} -2x+1}{x-1} =?\ $ $\displaystyle \lim\limits _{x\rightarrow -1}\frac{x^{3} +x+2}{x^{2} -1} =?\ $