If the curves $y ^ { 2 } = 6 x , 9 x ^ { 2 } + b y ^ { 2 } = 16$ intersect each other at right angles, then the value of $b$ is: (1) $\frac { 9 } { 2 }$ (2) 6 (3) $\frac { 7 } { 2 }$ (4) 4
If the curves $y ^ { 2 } = 6 x , 9 x ^ { 2 } + b y ^ { 2 } = 16$ intersect each other at right angles, then the value of $b$ is:\\
(1) $\frac { 9 } { 2 }$\\
(2) 6\\
(3) $\frac { 7 } { 2 }$\\
(4) 4