The value of $k$ for which the lines $7x - 8y + 5 = 0$,$3x - 4y + 5 = 0$ and $4x + 5y + k = 0$ are concurrent is given by

For $a, b, c \in R$,if $6 a^2-3 b^2-c^2+7 a b-a c+4 b c=0$ and $|a|+|b| \neq 0$,then all the lines given by $a x+b y+c=0$ are

If $4a^2 + 9b^2 - c^2 + 12ab = 0$, then the family of straight lines $ax + by + c = 0$ is concurrent at

If three non-zero real numbers $a, b, c$ are in harmonic progression,then the straight lines $\frac{x}{a} + \frac{y}{b} - \frac{2}{c} = 0$ are concurrent at the point

If $3x + 6y + 2 = 0$,$x + y + 1 = 0$,and $2x - y + 3 = 0$ are three given lines,then the point $\left(\frac{-4}{3}, \frac{1}{3}\right)$ is

The equation of the straight line passing through the point of intersection of the straight lines $3x - y + 2 = 0$ and $5x - 2y + 7 = 0$ and having an infinite slope is: