求极限((1-根号下x^2y+1)/x^3y^2)sin(xy),当x,y趋于0时

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求极限((1-根号下x^2y+1)/x^3y^2)sin(xy),当x,y趋于0时
求极限((1-根号下x^2y+1)/x^3y^2)sin(xy),当x,y趋于0时

求极限((1-根号下x^2y+1)/x^3y^2)sin(xy),当x,y趋于0时
lim((1-√(x^2y+1))/x^3y^2)sin(xy),有理化1-√(x^2y+1)):
=lim(-x^2y)/(1+√(x^2y+1))/x^3y^2)sin(xy)
=lim(-sin(xy))/(1+√(x^2y+1))/(xy)
=-1/2 (利用limsin(xy)/(xy)=1)

sqrt(1+x^2*y)~1+0.5*x^2*y;sin(x*y)~xy;
(1-sqrt(1+x^2*y))*sin(x*y)/(x^3*y^2)~(1-1-0.5*x^2*y)*x*y/(x^3*y^2)~-0.5

0
因为是相乘的关系,sin(xy)趋于0所以整体趋于0