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Differentiation Rules. Chain Rule Let y be a differentiable function of u and u be differentiable function of x , then The Chain Rule is sometimes stated: Let y=f(x) and u=g(x) with f differentiable at u = g(x ) and and g differentiable at x , then .
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Differentiation Rules • Chain Rule Let y be a differentiable function of u and u be differentiable function of x, then The Chain Rule is sometimes stated: Let y=f(x) and u=g(x) with f differentiable at u= g(x) and and g differentiable at x, then
Examples Problems
Example • A rocket is launched vertically. Radar is 5 km from launch site. When rocket is 13 km from radar this distance is increasing at 100 km/sec. Find rocket speed. • Let y = height of rocket, s = distance from rocket to radar • Must find dy/dt.
Different version • Rocket launched vertically 5 km from tracking station. When angle of elevation = 60, the rate of change of is 3/sec. What is the velocity at that instant (dy/dt)? Remember: = 60 = /3 radians
Derivatives of Inverse Functions • Let • Example: Find dy/dx if y = xx . Hint: ln y = ln (xx ) = x ln x.