If the co-ordinates of two points $A$ and $B$ are $( \sqrt { 7 } , 0 )$ and $( - \sqrt { 7 } , 0 )$ respectively and $P$ is any point on the conic, $9 x ^ { 2 } + 16 y ^ { 2 } = 144$, then $PA + PB$ is equal to : (1) 16 (2) 8 (3) 6 (4) 9
If the co-ordinates of two points $A$ and $B$ are $( \sqrt { 7 } , 0 )$ and $( - \sqrt { 7 } , 0 )$ respectively and $P$ is any point on the conic, $9 x ^ { 2 } + 16 y ^ { 2 } = 144$, then $PA + PB$ is equal to :\\
(1) 16\\
(2) 8\\
(3) 6\\
(4) 9