Answer:
Step-by-step explanation:
( g o h)(x) = g(h(x)) = g(3x) = 1/(3x+2)
( g o h)(x) exisit for 3x+2 ≠ 0
x ≠ -2/3
so the domain is : D = ]-∞:-2/3[ U] -2/3;+∞[