Homework

128^(3x)  = 8

128 = 2^7       and .....8   = 2^3      .....so we have....

[ 2^7]^(3x)  = 2^3

2^(21x)  = 2^3      since we have the bases the same, let's solve for the exponents

21x  = 3      divide both sides by 21

x = 3/21   = 1/7