Question

Efetue (5x4y2) ∙ (–2xy3) + (7x2y3) ∙ (–2x3y2) + (–20x5y5

Answer 1

$= - 5 {x}^{4} {y}^{2} \times 2x {y}^{3} - 7 {x}^{2} {y}^{3} \times 2 {x}^{3} {y}^{2} - 20 {x}^{5} {y}^{5} \\ \\ = - 44 {x}^{2} \times {x}^{2} \times x {y}^{2} \times {y}^{2} \times y \\ \\ \\ \\ = - 44 {x}^{5} {y}^{5} .$