Answer
$(2+5i)^{2} = -21+20i$
Work Step by Step
1. $(2+5i)^{2}$
2. Multiply $(2+5i)\times(2+5i)$(use the FOIL method to distribute the First, Outer, Inner, and Last terms):$4+10i+10i+25i^{2}$
3. Combine like terms: $4+20i+25i^{2}$
4. Change $25i^{2}$ to -25 because $i^{2} = -1$ and $25\times-1 = -25$:$4+20i-25$
5. Combine like terms:$-21+20i$
