When we are supposed to calculate the value of "temperature coefficient of resistance " i.e. α , how are we supposed to choose between the following two formulae :
α = (R2 - R1) / (R1*T2 - R2* T1 )
or
α = (R2 - R1)/ [ R1 *( T2-T1) ]
α = (R2 - R1) / (R1*T2 - R2* T1 )
or
α = (R2 - R1)/ [ R1 *( T2-T1) ]