Let x=1/y. :. x to -oo rArr y to 0.
:." The Reqd. Lim.="lim_(y to 0){-5/y^2+6/y+3}/sqrt{(1/y^4+1/y)^2+1},
=lim_(y to 0){1/y^2(-5+6y+3y^2)}/sqrt{(1+y^3)^2/y^8+1},
=lim_(y to 0){1/y^2(-5+6y+3y^2)}/sqrt{((1+y^3)^2+y^8)/y^8},
=lim_(y to 0)(1/y^2-:1/y^4)(-5+6y+3y^2)/sqrt((1+y^3)^2+y^8),
=lim_(y to 0) (y^2(-5+6y+3y^2))/sqrt((1+y^3)^2+y^8),
=(0(-5+0+0))/sqrt((1+0)^2+0),
=0.
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