E - F = (5xy - \(\dfrac{2}{3}\)x\(^2\)y + xyz\(^2\) - 1) - (2x\(^2\)y - xyz\(^2\) - \(\dfrac{2}{5}\)xy + x + \(\dfrac{1}{2}\))

= 5xy - \(\dfrac{2}{3}\)x\(^2\)y + xyz\(^2\) - 1 - 2x\(^2\)y + xyz\(^2\) + \(\dfrac{2}{5}\)xy - x - \(\dfrac{1}{2}\)

= (5xy + \(\dfrac{2}{5}\)xy) + (\(\dfrac{-2}{3}\)x\(^2\)y - 2x\(^2\)y) + (xyz\(^2\) + xyz\(^2\))+ (-1 - \(\dfrac{1}{2}\)) - x

= \(\dfrac{27}{5}\)xy - \(\dfrac{8}{3}\)x\(^2\)y + 2xyz\(^2\) - \(\dfrac{3}{2}\) - x

Vậy E - F = \(\dfrac{27}{5}\)xy - \(\dfrac{8}{3}\)x\(^2\)y + 2xyz\(^2\) - \(\dfrac{3}{2}\) - x

E + F = (5xy - \(\dfrac{2}{3}\)x\(^2\)y + xyz\(^2\) - 1) + (2x\(^2\)y - xyz\(^2\) - \(\dfrac{2}{5}\)xy + x + \(\dfrac{1}{2}\))

= 5xy - \(\dfrac{2}{3}\)x\(^2\)y + xyz\(^2\) - 1 + 2x\(^2\)y -xyz\(^2\) - \(\dfrac{2}{5}\)xy + x + \(\dfrac{1}{2}\)

= (5xy - \(\dfrac{2}{5}\)xy) + (\(\dfrac{-2}{3}\)x\(^2\)y + 2x\(^2\)y) + (xyz\(^2\) - xyz\(^2\)) + (-1 + \(\dfrac{1}{2}\)) + x

= \(\dfrac{23}{5}\)xy + \(\dfrac{4}{3}\) x\(^2\)y - \(\dfrac{1}{2}\) + x

nhờ nguyễn huy hải trả lời í cậu í giỏi lắm

L = (\(\dfrac{-3}{4}\)x\(^5\)y\(^4\)) . (xy\(^2\)) . (\(\dfrac{-8}{9}\)x\(^2\)y\(^5\))

= [(\(\dfrac{-3}{4}\)) . (\(\dfrac{-8}{9}\))] . (x\(^5\) . x . x\(^2\)) . (y\(^4\) . y\(^2\) . y\(^5\))

= \(\dfrac{2}{3}\)x\(^8\)y\(^{11}\)

- Bậc của đơn thức L là: 19

- Hệ số của đơn thức L là: \(\dfrac{2}{3}\)