Aus Online Mathematik Brückenkurs 2

When we remove the parentheses, the terms inside change sign,

\displaystyle 3i-(2-i)=3i-2+i\,\textrm{.}

Then, we collect together real and imaginary parts,

\displaystyle \begin{align} 3i-2+i &=-2+(3i+i)\\[5pt] &=-2+(3+1)i\\[5pt] &=-2+4i\,\textrm{.} \end{align}