7 yên 90 kg = ..... kg

560 hg = ........ kg

4 phút = 240 giây

1/3 phút = 20 giây

1/5 thế kỉ = 20 năm

1/4 thế kỉ = 25 năm

1/6 giờ = 600 giây

1/3 ngày = 8 giờ

1800dm² 40000cm² = 22 m²

7 yến 90kg = 790kg

560hg = 56kg

1, Would you to go out . No , thanks . I'd to stay ............at........home

2, If you're going to watch the football , you count me .....but.........I don't football

3,I've put ...................2 kg in the last month

4, The japanese eat headthily , she the live .............in.......a long time 

5, Sitting too close ...........on........the TV hurls your eyes

6, Becareful .......................what you eat and drink 

7. She runs six miles every day to help keep hersely .........................shape

8, Watching TV too mich isn't good ......in............your eyes a long time

1, Would you to go out . No , thanks . I'd rather stay .......at.............home

2, If you're going to watch the football , you count me ....out..........I don't football

3,I've put .....on..............2 kg in the last month

4, The japanese eat heathily , so the live ...for.................a long time 

5, Sitting too close ....to...............the TV hurls your eyes

6, Becareful ......with.................what you eat and drink 

7. She runs six miles every day to help keep herself ....in.....................shape

8, Watching TV too mich isn't good .....for.............your eyes a long time

Để \(\left(n+8\right)⋮\left(n+5\right)\) thì

\(\left(n+8\right)-\left(n+5\right)⋮\left(n+5\right)\)

\(\Rightarrow\)\(3⋮\left(n+5\right)\)

\(\Rightarrow\)​​\(\left(n+5\right)\inƯ\left(3\right)\)

\(\Rightarrow\)\(\left(n+5\right)\in\left(1;-1;3;-3\right)\)

\(\Rightarrow\)\(n\in\left(-4;-6;-2;-8\right)\)

Để \(\left(16-3n\right)⋮\left(n+4\right)\) thì

\(\left(16-3n\right)+\left(n+4\right)⋮\left(n+4\right)\)

\(\Rightarrow\)\(\left(16-3n\right)+3\left(n+4\right)⋮\left(n+4\right)\)

\(\Rightarrow\)\(16-3n+3n+12⋮\left(n+4\right)\)

\(\Rightarrow\)\(28⋮\left(n+4\right)\)

\(\Rightarrow\)\(\left(n+4\right)\inƯ\left(28\right)\)

\(\Rightarrow\)\(\left(n+4\right)\in\left\{\pm1;\pm2;\pm4;\pm7;\pm14;\pm28\right\}\)

\(\Rightarrow\)\(n\in\left\{-3;-4;-2;-6;0;-8;3;-11;10;-18;24;-32\right\}\)

Bài 1 : Gọi số thứ nhất cần tìm là x,số thứ hai cần tìm là y,số thứ ba cần tìm là z. Theo đề bài ta có :

x² + y² + z² = 8125

Mà \(y=\frac{2}{5}x\)=> \(5y=2x\)=> \(\frac{x}{5}=\frac{y}{2}\)(1)

\(y=\frac{3}{4}z\)=> 4y = 3z => \(\frac{y}{3}=\frac{z}{4}\)(2)

Từ (1) và (2) => \(\frac{x}{5}=\frac{y}{2};\frac{y}{3}=\frac{z}{4}\)

+) \(\frac{x}{5}=\frac{y}{2}\Rightarrow\frac{x}{15}=\frac{y}{6}\)

+) \(\frac{y}{3}=\frac{z}{4}\Rightarrow\frac{y}{6}=\frac{z}{8}\)

=> \(\frac{x}{15}=\frac{y}{6}=\frac{z}{8}\)

=> \(\frac{x^2}{15^2}=\frac{y^2}{6^2}=\frac{z^2}{8^2}\)

Áp dụng t/c dãy tỉ số bằng nhau ta có :

\(\frac{x^2}{15^2}=\frac{y^2}{6^2}=\frac{z^2}{8^2}=\frac{x^2+y^2+z^2}{15^2+6^2+8^2}=\frac{8125}{325}=25=5^2\)

=> x² = 5² . 15² = 75² => x = \(\pm\)75

y² = 5² . 6² = 30² => y = \(\pm\)30

z² = 5² . 8² = 40² => z = \(\pm\)40

Bài 2 tự làm