According to the principle of homogeneity of dimensions, powers of M, L,
T on either side of the formula must be equal. For this, on RHS, the
denominator (1−v2)1/2 should be dimensionless. Therefore,
instead of (1−v2)1/2,we should write (1−v2/c2)1/2.
Hence, the correct formula would be
m=m0(1−v2/c2)1/2