anh ơi em ko bt vì em mới lớp 2 anh thông cảm cho em nha 

\(\dfrac{x}{6}=\dfrac{7}{4}\Rightarrow x=\dfrac{6\cdot7}{4}=\dfrac{21}{2}\\ \dfrac{3}{x}=\dfrac{21}{17}\Rightarrow x=\dfrac{3\cdot17}{21}=\dfrac{17}{7}\)

Câu 2:
1.Do xy\(\perp\)CD mà zt\(\perp\)CD
\(=>xy//zt\)
2.\(=>\widehat{ABt}=\widehat{mAy}=46\left(haigocdongvi\right)\)

a)\(5x^2.\left(10x^4-5x^3+2\right)=50x^6-25x^5+10x^2\)

b) \(\left(x^2-5x+3\right).\left(-5x\right)=-5x^3+25x^2-15x\)

c) \(\left(5x-2y\right)\left(x^2-xy+1\right)=5x^3-5x^2y+5x-2x^2y+2xy^2-2y\\ =5x^3-7x^2y+2xy^2+5x-2y\)

d) \(\left(3x-2\right)\left(9x^2+6x-4\right)\\ =27x^3+18x^2-12x-18x^2-12x+8=27x^3+8\)

a) \(5x^2\left(10x^4-5x^3+2\right)=50x^6-25x^5+10x^2\)

b) \(\left(x^2-5x+3\right)\left(-5x\right)=-5x^3+25x^2-15x\)

c) \(\left(5x-2y\right)\left(x^2-xy+1\right)=5x^3-5x^2y+5x-2x^2y+2xy^2-2y=5x^3-7x^2y+2xy^2+5x-2y\)

d) \(\left(3x-2\right)\left(9x^2+6x-4\right)=27x^3+18x^2-12x-18x^2-12x+8=27x^3-24x+8\)

a: \(5x^2\left(10x^4-5x^3+2\right)=50x^6-25x^5+10x^2\)

b: \(\left(-5x\right)\left(x^2-5x+3\right)=-5x^3+25x^2-15x\)

c: \(\left(5x-2y\right)\left(x^2-xy+1\right)\)

\(=5x^3-5x^2y+5x-2x^2y+2xy^2-2y\)

\(=5x^3-7x^2y+2xy^2+3y\)

d: \(\left(3x-2\right)\left(9x^2+6x-4\right)\)

\(=27x^3+18x^2-12x-18x^2-12x+8\)

\(=27x^3-24x+8\)

c) C=(151515/161616 + 17^9/17^10)-(1500/1600 - 1616/1717)
      =(15/16 + 1/17)-(15/16 - 16/17) 
      = 15/16 ( 1/17 + 16/17)
      =15/16 . 1 = 15/16
       

áp dụng đúng công thức là ra

huhu

Grandpa was slept, visted,arrived

Grandpa was sleeping when the visitors arrived.

25 ko dùng in spite of mà dùng because of nhé

Because of being careless in writing, he got bad marks

26 In spite of being ill, she insisted on going to work

27 In spite of my trying to persuade her, i didn't succeed