\[\begin {array} {1 1} (1)\;4x^2+5xy-6y^2-11x+11y+50=0 \\ (2)\;4x^2+5xy-6y^2-11x+11y-43=0 \\ (3)\;4x^2-5xy-6y^2-11x+11y+57=0 & \\ (4)\;x^2-5xy-y^2-11x+11y-43=0 \end {array}\]