Michel-Joseph wrote at 2014-12-10 00:41:03
the solution of part A is wrong...

y'(x=9)=9/(225-81)*?=3/4 feet/sec.

You forgot to multiply by dx/dt the above expression!

the solution of part B is also wrong...

You should be more careful when you answer students questions.  


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Alon Mandes


Kind of questions I can answer : Limits, Derivatives, Integration, Implicit functions, continuousity, differentiation ,Extremum problems, Lagrange multipliers, Gradients, Surface integrals, Multi variables functions ,Multi variables Integrals,Complex variables ,Complex functions, Curves, Trajectory integrals & Vector analyse,Divergence,Rotor & word problems. Kind of question I can't answer : Economics,Combinatorics,infinite series & convergence ,Statistics & Probabilities .


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