Appendix A - Review - A.7 Complex Numbers; Quadratic Equations in the Complex Number System - A.7 Assess Your Understanding - Page A60: 33

$2i$

Use special formula $(a+b)^2=a^2+2ab+b^2$. We have $a= 1$ and $b=i $ $(1+i)^2=(1)^2+2(1)(i)+(i)^2$ Simplify. $=1+2i+i^2$ Use $i^2=-1$. $=1+2i+(-1)$ Simplify. $=2i$ Hence, the solution in the standard form is $2i$.