How to lay out maths answers which involve the approximately equals sign

For example let's say that:

e^x sin(x) ~= ( 1 + x + (1/2)x^2 + (1/6)x^3 )( x - (1/6)x^3 )

and I now want to simplify the right hand side of the equation.
DoI repeatedly use the approximately equals sign or do I only use it once?

e.g. e^x sin(x) ~= (1 + x + (1/2)x^2 + (1/6)x^3)(x - (1/6)x^3)
= x + x^2 + (1/3)x^3 + ...

or must you keep the approximately equals sign in:

e.g. e^x sin(x) ~= (1 + x + (1/2)x^2 + (1/6)x^3)(x - (1/6)x^3)
~= x + x^2 + (1/3)x^3 + ...

Thank you for your time.

Hello,

sin(x).e^x ≈ (1 + x + x²/2 + x³/6)(x - x³/6)

= = = = = = = = = = = = = = = = = =
Usually,