Richard Skinner
rls2723
Sheet #25
Week #4
Problem 3.5.7
http://208.166.239.244/3_5_7.htm

The temperature in a square plate is given by the equation T = x + 3y. An ant crawled on the plate along the parabolic path y = x2 until it reached the point (2,4), whereupon it found itself fried. What is wrong with the following argument?

We can cancel the two equal terms, concluding that

.

Substituting the given functions and numbers, we learn that

12 = 0.

Solution:

Some parameters must be introduced before the chain rule will work.

x = t

y = t2

Now rewrite the chain rule argument to reflect the new parameters.

All that is left is substituting in the values and simplifying to find the answer.

= (1)*(1) + (3 * 2t)

=6t + 1