Given: z = (2 – 5i)²

First we calculate (2 – 5i)² and then we find the conjugate

(2 – 5i)² = (2)² + (5i)² – 2(2)(5i)

= 4 + 25i² – 20i

= 4 + 25(-1) – 20i [∵ i² = -1]

= 4 – 25 – 20i

= -21 – 20i

Now, we have to find the conjugate of (-21 – 20i)

So, the conjugate of (- 21 – 20i) is (-21 + 20i)