Forced Response Test Bank Question
The step where you canceled out (2j + 1) / 2j does not look right.

Subsequent values are going to change. In any case:

1 / (1 + 2j) does not equal to (1 + 1/2 j).

One standard way of getting rid of a complex value in the denominator is to multiply top and bottom with the complex conjugate of the denominator.

When everything are fixed, convert final answer to polar form and there you have the amplitude and phase.