Find the conjugate of each of the following:

Given: $z=(2-5 i)^{2}$

First we calculate $(2-5 \mathrm{i})^{2}$ and then we find the conjugate

$(2-5 i)^{2}=(2)^{2}+(5 i)^{2}-2(2)(5 i)$

$=4+25 i^{2}-20 i$

$=4+25(-1)-20 i\left[\because i^{2}=-1\right]$

$=4-25-20 i$

$=-21-20 i$

Now, we have to find the conjugate of $(-21-20 \mathrm{i})$

So, the conjugate of $(-21-20 \mathrm{i})$ is $(-21+20 \mathrm{i})$