$3$ Calcular los siguientes límites. a) $\right)$ $lim _{x→0}\dfrac {x+1} {x-1}$ b) $\right)$ $lim _{t→\infty }\dfrac {t^{2}-2t+3} {2t^{2}+5t-3}$ $c\right)$ $lim _{x→0}\left(\times +1\right)^{x}$ d) $\right)$ $x→\infty ^{7\dfrac {x2} {x+1}}$ $\tarc{w} $ $lim _{x→1}\dfrac {5} {x-1}$ $f\right)$ $lim _{x→3}\dfrac {x} {\sqrt{x+1} }$ $g\right)$ $lim _{x→0}\left(\dfrac {\sqrt{x+1} } {x}\right)^{x+1}$ h) $\right)$ $lim _{x→-2}\dfrac {x^{2}+3x+2} {x+2}$