Explanation:
what you wrote was

or (it is the same)

but what your picture says is
![\sqrt[3]{40}](https://img.qammunity.org/2024/formulas/mathematics/college/mr0p4xr9vjwmap5q28yzqamb9w31los8p9.png)
that is totally different.
that is the cubic root of 40.
in other words we are looking for the x when
x³ = 40
just for control, we know
3³ = 27
4³ = 64
so, x must be a value between 3 and 4, but a little bit closer to 3 than to 4.
using a calculator we get
![\sqrt[3]{40} = 3.419951893...](https://img.qammunity.org/2024/formulas/mathematics/college/oekb0dmui78sjffzzu6l2r01f7z5ef238m.png)
and that is rounded to 4 decimal places
3.4200 = 3.42