1.求下列极限.-|||-(1) lim _(xarrow -2)(3(x)^2-5x+2) --|||-(4) lim _(xarrow 1)dfrac ({x)^2-1}(2{x)^2-x-1}-|||-(7) lim _(xarrow infty )dfrac ({(2x-1))^30((3x-2))^20}({(2x+1))^50}-|||-(10) lim _(xarrow 0)dfrac (sin 2x)(sin 3x)-|||-(2) lim _(xarrow sqrt {3)}dfrac ({x)^2-3}({x)^4+(x)^2+1}-|||-(5) lim _(harrow 0)dfrac ({(x+h))^3-(x)^3}(h)-|||-(8) lim _(xarrow 0)dfrac ({x)^2}(1-sqrt {1+{x)^2}} --|||-(11) lim _(xarrow 0)((dfrac {2-x)(2))}^dfrac (2{x)}-|||-(3) lim _(xarrow 2)dfrac ({x)^2-3}(x-2) .-|||-(6) lim _(xarrow infty )dfrac (2x+3)(6x-1)-|||-(9) lim _(xarrow 0)dfrac (tan x-sin x)(x)-|||-(12) lim _(xarrow infty )((dfrac {x-1)(x+1))}^x