Questions in pair-st-lines

Select	Question
	The equation of the lines passing through the origin and parallel to the lines represented by the equation $2{{x}^{2}}-xy-6{{y}^{2}}+7x+21y-15=0$, is
	The equation $2{{x}^{2}}+4xy-p{{y}^{2}}+4x+qy+1=0$ will represent two mutually perpendicular straight lines, if
	If the equation $A{{x}^{2}}+2Bxy+C{{y}^{2}}+Dx+Ey+F=0$ represents a pair of straight lines, then ${{B}^{2}}-AC$
	The equation of the lines passing through the origin and having slopes 3 and $-\frac{1}{3}$ is
	The equation $xy+{{a}^{2}}=a(x+y)$ represents
	If the slope of one of the line represented by the equation $a{{x}^{2}}+2hxy+b{{y}^{2}}=0$ be $\lambda$ times that of the other, then
	If one of the line represented by the equation $a{{x}^{2}}+2hxy+b{{y}^{2}}=0$ is coincident with one of the line represented by ${a}'{{x}^{2}}+2{h}'xy+{b}'{{y}^{2}}=0$, then
	The equation $4{{x}^{2}}+12xy+9{{y}^{2}}+2gx+2fy+c=0$ will represents two real parallel straight lines, if
	The equation $2{{y}^{2}}-xy-{{x}^{2}}+6x-8=0$ represents
	One of the lines represented by the equation ${{x}^{2}}+6xy=0$ is