express 2(cos 4pi/3 + i sin 4pi/3) in the form x+iy

2[-0.5 +(-i 0.866)]

looks good to me, though you should probably expand it out to the desired form.

-1 - √3 i

To express the given complex number in the form x + iy, we need to simplify it using Euler's formula. Euler's formula states that e^(iθ) = cos(θ) + i sin(θ), where i is the imaginary unit.

Let's simplify the expression step by step:

First, let's rewrite the given number using Euler's formula:
cos(4π/3) + i sin(4π/3)

Using Euler's formula, this becomes:
e^(i(4π/3))

Now, we can rewrite e^(i(4π/3)) using the complex exponential form:
e^(iθ) = cos(θ) + i sin(θ)

θ = 4π/3

So, e^(i(4π/3)) = cos(4π/3) + i sin(4π/3)

Therefore, we can express the given complex number in the form x + iy as:
2(cos(4π/3) + i sin(4π/3))

Thus, the final expression is:
2cos(4π/3) + 2i sin(4π/3)