(i) (2x +5y) (2x + 3y)

= (2x)^{2} + (5y + 3y) (2x) + (5y) (3y)

= 4x^{2} + 16xy + 15y^{2}

(ii) (2a^{2} +9) (2a^{2} + 5)

= (2a^{2})^{2} + (9 + 5) (2a^{2}) + (9) (5)

= 4a^{4} + 28a^{2} + 45

(vii) (xyz − 4) (xyz − 2)

+ (xyz)^{2} + [ (-4) + (-2) ] (xyz) + (-4) (-2)

= x^{2}y^{2}z^{2} - 6xyz + 8