1.计算下列极限:-|||-(1) lim _(xarrow 2)dfrac ({x)^2+5}(x-3) =-|||-(4) lim _(xarrow 1)dfrac (4{x)^3-2(x)^2+x}(3{x)^2+2x} =-|||-(7) lim _(xarrow infty )dfrac ({x)^2-1}(2{x)^2-x-1} =-|||-(2) lim _(xarrow sqrt {3)}dfrac ({x)^2-3}({x)^2+1} =-|||-(5) lim _(harrow 0)dfrac ({(x+h))^2-h}(h) =-|||-(8) lim _(xarrow infty )dfrac ({x)^3+x}({x)^4-3(x)^2+1} ;-|||-(3) lim _(xarrow 1)dfrac ({x)^2-2x}({x)^2-1} =-|||-(6) lim _(xarrow infty )(2-dfrac (1)(x)+dfrac (1)({x)^2}) =-|||-(9) lim _(xarrow 4)dfrac ({x)^2-6x+8}({x)^2-5x+4} =