1.计算下列极限:-|||-(1) lim _(xarrow 2)dfrac ({x)^2+5}(x-3) ;-|||-(4) lim _(xarrow 0)dfrac (4{x)^3-2(x)^2+x}(3{x)^2+2x} ;-|||-(2) lim _(xarrow sqrt {3)}dfrac ({x)^2-3}({x)^2+1} ;-|||-(5) lim _(harrow 0)dfrac ({(x+h))^2-(x)^2}(h)-|||-(3) lim _(xarrow 1)dfrac ({x)^2-2x+1}({x)^2-1} ;-|||-(6) lim _(xarrow infty )(2-dfrac (1)(x)+dfrac (1)({x)^2}) ;1.计算下列极限:-|||-(1) lim _(xarrow 2)dfrac ({x)^2+5}(x-3) ;-|||-(4) lim _(xarrow 0)dfrac (4{x)^3-2(x)^2+x}(3{x)^2+2x} ;-|||-(2) lim _(xarrow sqrt {3)}dfrac ({x)^2-3}({x)^2+1} ;-|||-(5) lim _(harrow 0)dfrac ({(x+h))^2-(x)^2}(h)-|||-(3) lim _(xarrow 1)dfrac ({x)^2-2x+1}({x)^2-1} ;-|||-(6) lim _(xarrow infty )(2-dfrac (1)(x)+dfrac (1)({x)^2}) ;