Related rates car problem

Pythagoras Theorem A^2+B^2=C^2

 

NO you have to do the dy/dx to get the incresing speed!

 

And put the dy/dx on it dc/dt(2c) = da/dt(2a)+db/dt(2b)!
but you have to calculate how much have they both travel in 2 hour and put into the equation and solve!

 

NO you have to calculate how much have they both travel in 2 hour

dy/dx is the speed a b and c is distance~!

 

yep , and plug the speed and the distance into equation and solve and the third distance between you have to calculate that too. use the Pythagoras Theorem you have already found up there!

 

I am starting to wonder if you are serious! You cannot differentiate c²= a²+ b² and get 2c= 2a+ 2b. For one thing, you have completely left out the question of which variable you are differentiating with respect to. Here the question is about how fast the distance between them, c, is increasing so you are trying to find dc/dt,, not c.
As yaho8888 alrready told you, you need to differentiate both sides of c²= a²+ b² with respect to x! Using the chain rule, that is 2c dc/dt= 2a da/dt+ 2b db/dt. Now what are a, b, c, da/dt, and db/dt after two hours?
(And c, the distance between the cars after 2 hours, is NOT 170 miles.

 

NO!
you have to solve for dc/dt~!
The question ask you for speed! dx/dy means speed remember that.

dc/dt(2c) = da/dt(2a)+db/dt(2b)
first solve the distance between a and b in two hours use Pythagoras Theorem.
(2*60mi/hr)^2+(2*25mi/hr)^2= c^2
if you calculate that out c = 130miles

you found the c plug into the equation~!
dc/dt(2*130miles) = (60mi/hr)*(2*120mi) +(25mi/hr)*(2*50mi)
then just solve for dc/dt~!
which is 65mile/hr!

 

Man you have no Idea what calculus is!