Two resistances R1 and R2 are made of different materials. The temperature coefficient of resistance of material R1 is α and that of material R2 is-β. The resistance of the series combination of R1 and R2 will not change with temperature if R1/R2 is equal to
(1) α/β
(2) (α + β) (α − β)
(3) (α2 + β2)/2αβ
(4) β/α
