If x2+2xy+ky2+4x−2y+l=0 represents pair of perpendicular lines then

The equation ax2+2hxy+by2+2gx+2fy+c=0 represents pair of lines if ahghbfgfc=0 Given that the equation x2+2xy+ky2+4x−2y+l=0represents a pair of perpendicular lines If they are perpendicular lines a+b=0Hence, k+1=0⇒k=−1Consider the condition for representing a pair of lines, substitute k=−11121−1−12−1l=1−l−1−1l+2+2−1+2=−1−l−l−2+2=−1−2lHence,1+2l=0l=−12Therefore, l=−12 and k=−1