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Đáp án:

a) 3 giờ.

b) 8 m/s, 120m.

Giải thích các bước giải:

a) Thời gian con rùa bơi được 7,5km là:

`t = s/v = 7,5 : 2,5 ...

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Lee: Goodnight :3

`#NqHahh`

`a, P(x) + Q(x)`

`= (x^3 - 2x + 1) + (2x^2 - 2x^3 + x - 5)`

`= x^3 - 2x + 1 + 2x^2 - 2x^3 + x - 5`

`= (x^3 - 2x^3) + 2x^2 + (-2x + x) + (1 - 5)`

`= -x^3 ...

`#NqHahh`

Câu 1:

`a) (-4)/9 . 5(3)/7 + 3(4)/7 . (-4)/9 - 1/2`

`= (-4)/9 . 38/7 + 25/7 . (-4)/9 - 1/2`

`= (-4)/9 . (38/7 + 25/7) - 1/2`

`= ( ...

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`***` $\color{#FF99FF}{\text{N}}$$\color{#CC99FF}{\text{qH}}$$\color{#9999FF}{\text{a}}$$\color{#6699FF}{\text{h}}$$\color{#6699CC}{\text{h}}$

Lee: Tus vẽ đẹp quáaaaaaa

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`***` $\color{#FF99FF}{\text{N}}$$\color{#CC99FF}{\text{qH}}$$\color{#9999FF}{\text{a}}$$\color{#6699FF}{\text{h}}$$\color{#6699CC}{\text{h}}$

[Tặng Cuaaa ]

`#NqHahh`

2.

a) `(-1)/6 . 3/5 . n + (-0,5)^2 = 3`

`(-1)/10 . n + 1/4 = 3`

`(-1)/10 . n = 3 - 1/4`

`(-1)/10 . n = 11/4`

`n = 11/4 : (-1)/10 = 11/4 . (-10)`< ...