this is wrong. but can you explain how to correct it? thanks

Question

use differential of x^-1/3 to approximate solution to (1/cube root(7.952))

differential: df= -1/3(x^(-4/3)) * dx

df= -1/48 * 0.0048
df= -0.001
0.500 - 0.001 = 0.499

but this is wrong.

Answer 1

dx = -0.048

df = 0.001

Answer 2

This is also what I entered, yet it is wrong