State the chain rules for one or two independent variables.
Use tree diagrams as an aid to understanding the chain rule for several independent and intermediate variables.
Perform implicit differentiation of a function of two or more variables.
In single-variable calculus, we found that one of the most useful differentiation rules is the chain rule, which allows us to find the derivative of the composition of two functions. The same thing is true for multivariable calculus, but this time we have to deal with more than one form of the chain rule. In this section, we study extensions of the chain rule and learn how to take derivatives of compositions of functions of more than one variable.
Chain rules for one or two independent variables
Recall that the chain rule for the derivative of a composite of two functions can be written in the form
In this equation, both
$f\left(x\right)$ and
$g\left(x\right)$ are functions of one variable. Now suppose that
$f$ is a function of two variables and
$g$ is a function of one variable. Or perhaps they are both functions of two variables, or even more. How would we calculate the derivative in these cases? The following theorem gives us the answer for the case of one independent variable.
Chain rule for one independent variable
Suppose that
$x=g\left(t\right)$ and
$y=h\left(t\right)$ are differentiable functions of
$t$ and
$z=f\left(x,y\right)$ is a differentiable function of
$x\phantom{\rule{0.2em}{0ex}}\text{and}\phantom{\rule{0.2em}{0ex}}y.$ Then
$z=f\left(x\left(t\right),y\left(t\right)\right)$ is a differentiable function of
$t$ and
where the ordinary derivatives are evaluated at
$t$ and the partial derivatives are evaluated at
$\left(x,y\right).$
Proof
The proof of this theorem uses the definition of differentiability of a function of two variables. Suppose that
f is differentiable at the point
$P\left({x}_{0},{y}_{0}\right),$ where
${x}_{0}=g\left({t}_{0}\right)$ and
${y}_{0}=h\left({t}_{0}\right)$ for a fixed value of
${t}_{0}.$ We wish to prove that
$z=f\left(x\left(t\right),y\left(t\right)\right)$ is differentiable at
$t={t}_{0}$ and that
[link] holds at that point as well.
where
$\underset{\left(x,y\right)\to \left({x}_{0},{y}_{0}\right)}{\text{lim}}\frac{E\left(x,y\right)}{\sqrt{{\left(x-{x}_{0}\right)}^{2}+{\left(y-{y}_{0}\right)}^{2}}}=0.$ We then subtract
${z}_{0}=f\left({x}_{0},{y}_{0}\right)$ from both sides of this equation:
As
$t$ approaches
${t}_{0},$$\left(x\left(t\right),y\left(t\right)\right)$ approaches
$\left(x\left({t}_{0}\right),y\left({t}_{0}\right)\right),$ so we can rewrite the last product as
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest.
Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.?
How this robot is carried to required site of body cell.?
what will be the carrier material and how can be detected that correct delivery of drug is done
Rafiq
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
how did you get the value of 2000N.What calculations are needed to arrive at it