A) \[-5/3\]
B) \[+\,5/3\]
C) \[1/3\]
D) \[-1/3\]
Correct Answer: A
Solution :
Equation of a pair of lines\[2{{x}^{2}}+4xy-k{{y}^{2}}+4x+2y-1=0\] the standard equation \[a{{x}^{2}}+2hxy+b{{y}^{2}}+2gx+2fy+c=0\]and comparing \[a=2,\,b=-k,\,f=1,\] \[g=2,c=-1\]and \[h=2.\] Hence equation represents a pair of lines, therefore \[abc+2fgh-a{{f}^{2}}-b{{g}^{2}}-c{{h}^{2}}=0\]\[\Rightarrow \]\[2k+8-2+4k+4=0\Rightarrow 6k=-10\] \[k=-5/3\]You need to login to perform this action.
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