Suppose y = √ 2 x + 1 , where x and y are functions of t

[Dhanalakshmi]

Suppose y = √ 2 x + 1 , where x and y are functions of t .
a) if dx / dt = 9 , find dy / dt when x = 4 .
b) If dy / dt = 2 , find dx / dt when x = 12 .