A) -5
B) 5
C) 1
D) 0
Correct Answer: A
Solution :
Since the lines \[x+3y-9=0,\] \[4x+by-2=0\] and \[2x-y-4=0\]are concurrent, then \[\left| \begin{matrix} 1 & 3 & -9 \\ 4 & b & -2 \\ 2 & -1 & -4 \\ \end{matrix} \right|=0\] \[\Rightarrow \]\[1(-4b-2)-3(-16+4)-9(-4-2b)=0\] \[\Rightarrow \] \[-4b-2+36+36+18b=0\] \[\Rightarrow \] \[14b+70=0\] \[\Rightarrow \] \[b=-5\]You need to login to perform this action.
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