b) (–2x – 5y)(2x – 5y);

b) (–2x – 5y)(2x – 5y)= ‒[(2x + 5y)(2x – 5y)]

= ‒ [(2x)² ‒ (5y)²] = ‒(4x² ‒ 25y²) = 25y² ‒ 4x².