If $P$$\left (x, y \right)$ is any point on the line joining the points $A$$\left (a, 0 \right)$ and $B$$\left(0, b \right)$ then the value of $bx+ay-ab$ is :
Correct option is C.
Just take x = 0 or y=0 and substitute in equation.
As $P(x,y)$ is any point on the line joining the points $A$ and $B$,
Take $P(x,y) = A(a,0) \implies x=a,y=0$
$bx +ay – ab = ba + a\cdot0- ab = 0$