A) (2a+3b)(4a²-6ab+9b²) b) (5-2y)(25x²+10xy+4y²) c) (m²-m+2)(3m²-2) d) (5-2a+a²)(4a²-3a-1)

$a)8 {a}^{3} - 12 {a}^{2} b + 18 {ab}^{2} + 12 {a}^{2} b \\ - 18 {ab}^{2} + 27 {b}^{3} = 8 {a}^{3}$ +27b^3
$b)125 {x}^{2} + 50xy + 20 {y}^{2} - 50 {x}^{2} y \\ - 20 {xy}^{2} - 8 {y}^{3}$
$c)3 {m}^{4} - 2 {m}^{2} - {3m}^{3} + 2m \\ + {6m}^{2} - 4 = 3 {m}^{4} + {4m}^{2} - {3m}^{3} \\ + 2m$
$d)20 {a}^{2} - 15a - 5 - 8 {a}^{3} + 6 {a}^{2} \\ + 2a + 4 {a}^{4} - 3 {a}^{3} - {a}^{2} = \\ 25{a}^{2} - 13a - 5 - 11 {a}^{3} + 4 {a}^{4}$