Answer:
13
Step-by-step explanation:
(x + 3)^3/2 = 64
√(x + 3)^3 = 64
(x + 3)^3 = 64^2
(x + 3)^3 = (4^3)^2
(x + 3)^3 = (4^2)^3
Same exponent
So
x + 3 = 4^2
x + 3 = 16
x = 13