and yet another question......

A car is driving northwest at v mph across a sloping plain whose height, in feet above sea level, at a point N miles north and E miles east of a city is given by
h(N,E)=3000+75N+75E.
(a) At what rate is the height above sea level changing with respect to distance in the direction the car is driving?
rate =
(b) Express the rate of change of the height of the car with respect to time in terms of v.
rate =

Question

and yet another question......

A car is driving northwest at v mph across a sloping plain whose height, in feet above sea level, at a point N miles north and E miles east of a city is given by
h(N,E)=3000+75N+75E.
(a) At what rate is the height above sea level changing with respect to distance in the direction the car is driving? 
rate = 
(b) Express the rate of change of the height of the car with respect to time in terms of v. 
rate =

anonymous · Answer

grad f =<75,75>, so the rate of change is the mag of that....well, i put in sqrt (75^2+75^2> and webwork said no.............

yanasidlinskiy · Answer

A.) 
$dh \div dt=75\times dN \div dt +100 dE \div dt$

 where, 

$dN \div dt =V \cos 45$

$dE/dt=-V \cos 45$
Find: $dh \div dt$
Rate is the height above sea level changing with respect to distance in the direction the car is driving= rate is the height above sea level changing with respect to distance in the direction the car is driving= $V -dh \div dt$  Solve:)

anonymous · Answer

those aren't even the numbers i need to work with....and this is something that was just copy and pasted from yahoo answers that i looked at and was incorrect.