【题目】-|||-(11) lim _(narrow infty )sqrt [n]({2)^n+(3)^n+(4)^n}= __-|||-(12)设 lim _(xarrow -1)dfrac ({x)^3+a(x)^2+x+2}(x+1)=b b为有限数),则 a+b= __-|||-(13) lim _(xarrow infty )(xsin dfrac (1)(x)+dfrac (1)(x)sin x)= __-|||-(14) lim _(xarrow 0)(xsin dfrac (1)(x)+dfrac (1)(x)sin x)= __-|||-(15)设 lim _(xarrow infty )((dfrac {x+2a)(x-1))}^2=(e)^3, 则 a= __ _,-|||-(16) lim _(xarrow 0)sqrt [4](1-2x)= __-|||-(17)已知 (x)=2x+4sin xlim _(xarrow dfrac {pi )(2)}f(x), 则 f(x)= __-|||-(18)已知 f(x)=-|||-+a,xgeqslant 0 在 x=0 处连续,则 a= __ ---|||-(19)若函数 f(x)= { cdot xlt 0 a+cos xcdot xgt 0 a+cos x,xgt 0 的连续区间为 __ -