Question

The answer is (3). Please explain it...

Answer 1

Answer:

obviously time T2 is less than time T1 so its sure that T1-T2 will give positive value and a non zero value therefore T1-T2 is justified ...

T2T1 came because of the calculation which is

.

.

1/T =(1/T2)-(1/T1)

T =T2T1/T1-T2

hope it helps

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