The Mistake Fragment

Find the algebra mistake:

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The Correction

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An Explanation

There are two mistakes.
The first π is not part of the denominator and should be combined with the numerator of the second fraction.
The denominators have not been combined correctly - the 2 in the first denominator has to be distributed across both the 4 and the π in the second denominator (or left in factored form, as shown in the middle step of the corrected version).