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.#
Enjoy Maths.!