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giúp mik đi màaaaaaa

Giúp mk vs mn ơi 

Bài 1:

\(a,A=x^2y^3-\dfrac{5}{4}\cdot\dfrac{4}{5}x^2y^3=x^2y^3-x^2y^3=0\\ b,B=\dfrac{1}{2}a^3b^2-\dfrac{2}{3}a^3b^2=-\dfrac{1}{6}a^3b^2\)

Bài 2:

\(A=-3x^3y^3z-5x^3y^3z=-8x^3y^3z\)

Bài 3:

\(=-3x^2y^2+4x^2y^2=x^2y^2\)

Vì \(x^2\ge0;y^2\ge0\Leftrightarrow x^2y^2\ge0\left(đpcm\right)\)

số nào lớn nhất là bé nhất số nào bé nhất là lớn nhất

Quy đồng : 

\(\dfrac{1}{2}\) = \(\dfrac{\text{1 × 30}}{\text{2 × 30 }}\) = \(\dfrac{30}{60}\)

\(\dfrac{2}{3}\) = \(\dfrac{\text{2 × 20}}{\text{3 × 20 }}\) = \(\dfrac{40}{60}\)

\(\dfrac{3}{4}\) = \(\dfrac{\text{3 × 15 }}{4×15}\) = \(\dfrac{45}{60}\)

\(\dfrac{4}{5}\) =\(\dfrac{\text{4 × 12 }}{5×12}\) = \(\dfrac{48}{60}\)

\(\dfrac{5}{6}\) = \(\dfrac{\text{5 × 10 }}{6×10}\) = \(\dfrac{50}{60}\)

⇒ 30 < 40 < 45 < 48 < 50

\(\dfrac{1}{2}\) < \(\dfrac{2}{3}\) < \(\dfrac{3}{4}\) < \(\dfrac{4}{5}\) < \(\dfrac{5}{6}\)

\(\dfrac{1}{2}\) ; \(\dfrac{2}{3}\) ; \(\dfrac{3}{4}\) ; \(\dfrac{4}{5}\) ; \(\dfrac{5}{6}\)

32. Tom is strong so he can lift that heavy table

33. Nam's father used to drink a lot of wine

34. We have been in Sapa for 2 years

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36.He climbed a tree in order to get  a better view

37. Did Jame Watt invent the steam engine?

38. This is the first time she has seen a more unusal festival than this

39. An important experiment is being carry out by the scientists

40. Cheese is made from milk

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