Question

Find

dy/dt
where
y = 2 sqrt(2)− 4
and
dx/dt = 9
when
x = 4.

I found the derivative of y=2sqrt(2)-4 but I am stuck as to where to plug in dx/dt

Answer 1

y = 2√x - 4

since x and y are both functions of t, think chain rule:

dy/dt = 1/√x dx/dt

Now just plug in your numbers and you have

dy/dt = 1/2 * 9