Changing Limits of Integration affects variable substitution?

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Changing the limits of integration during variable substitution in integrals is crucial for accurate results. When substituting a variable, it's often simpler to use a different dummy variable to avoid confusion. For example, substituting t with u(t) = t/2 requires adjusting the integral's limits accordingly, transforming it into a new integral with the updated bounds. This method ensures that the integral remains correctly defined and reflects the original function's behavior. Properly applying these techniques is essential for solving integrals accurately.
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not exactly sure what the question is...

couple of points though, it is usually easier to use a different dummy variable when you use a subtitution

say you have
\int_b^a dt f(t)

and want to change to u(t) = t/2, then
t=2u
dt = 2.du
u(a) = a/2
u(b) = b/2

so the integral becomes
\int_{b/2}^{a/2} 2.du f(2u)

see how this compares with your case...
 
thanks
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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