We will first find dy/dx, then calculate dy/dt = dy/dx dx/dt
We can find dy/dx either by first writing y as a function of x or using implicit differentiation.
Let's do it both ways and show that the results are the same.
Writing y as a function of x, as 6y2 = x5 - x7 and y > 0,
y = √(( x5 - x7 )/6)
Then, dy/dx = (5x4 - 7x6 )/(12√(( x5 - x7 )/6)). Note that this equals (5x4 - 7x6 )/(12 y)
If we use implicit differentiation, we get 12y dy = 5x4 - 7x6 or
dy/dx = (5x4 - 7x6 )/(12y)
This equals our result calculated the other way.
We are given that x = 1/5 and dx/dt = 6
When x = 1/5, y = √(( x5 - x7 )/6) = √(( 1/55 - 1/57 )/6) = 5-7/2 * √((25-1)/6) = 2 * 5-7/2
Then, dy/dx = (5x4 - 7x6 )/(12y) = 5-6 (5*25 - 7)/(12 * 2 * 5-7/2 ) = 5-5/2 (59/12)
dx/dt = 6
Thus, dy/dt = dy/dx * dx/dt = 5-5/2 (59/12) * 6 = 59 * 5-5/2 /2 or 59/(2*55/2) or 59√5/250