Hi I will be collecting your homework tomorrow Chain Rule How to differentiate a composition. Y is a...
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Transcript of Hi I will be collecting your homework tomorrow Chain Rule How to differentiate a composition. Y is a...
Hi
I will be collecting your homework
tomorrow
Chain RuleHow to differentiate a composition.
Y is a function of u, and u is a function of x
Basic Idea:
dx
du
du
dy
dx
dy
Compositions
• Let
• Write each as a composition of 2 or more functions
23)(2)(,)cos()( xxhandxxgxxf
)32cos(6)cos(3
)27cos(2)cos(
2
4
xyxy
xyxy
More Composition review
• Given the functions, find
))((
)(
)(
7)(1)(,sin)( 2
xhgfhg
xh
xgfgf
xxhandxxgxxf
Let’s talk with math dude…
So how do we differentiate a composition?
The idea is stuck to my
head
Let y = 14x-8
• Let’s write y = 2(7x-4).• See a composition?• Y = 2u and u = 7x-4
• Find• dy/du= du/dx = dy/dx =
(2)(7)=14
dy/du • du/dx = dy/dx
Math dude’s gear idea was pretty intuitive …do you know why?
• If y is a function of u, and u is a function of x then,
• www.mathizaverb.com see chain rule link under calculus corkboard.
dx
du
du
dy
dx
dy
Chain Rule Again
• If f is differentiable at u, which is really g(x) and g is differentiable at x, then f◦g(x) is differentiable at x and….
function notation
)())(()( xgxgfxgf
Examples and Problems
Differentiate each.
253
22
32
)42(
)3(sin)243(
22
313
xxyxy
yxxy
xyxy
1. Assume that h(x) = f( g(x) ) , where both f and g are differentiable functions. If g(-1)=2, g'(-1)=3, and f '(2)=-4 , what is the value of h'(-1) ?
2. Assume that , h(x)= (f(x))3 where f is a differentiable function. If f(0) = -1/2 and f ‘ (0) = 8/3 , determine an equation of the line tangent to the graph of h at x=0.
Problems to Deepen Understanding
SolutionsSolution to problem 1
Solution to problem 2
Physics
• A particle moves along a straight line with displacement s(t) , velocity v(t) and accel a(t). Show
• Hint: Write accel, veloc. in terms of differentials, then apply chain rule.
• What is the meaning of dv/dt and dv/ds?
ds
dvtvta )()(