uh hu?

xy + 2x + 2y = 5

xy + 2x + 2y + 4 = 9

(x + 2)(y + 2) = 9

x + 2 = 3
y + 2 = 3

x = 1
y = 1

x,y=1

Ta có:

• \(gcd ⁡ \left(\right. a , b \left.\right) = 15\)
• \(l c m \left(\right. a , b \left.\right) = 1260\)

Áp dụng hệ thức:

\(a \cdot b = gcd ⁡ \left(\right. a , b \left.\right) \cdot l c m \left(\right. a , b \left.\right) = 15 \cdot 1260 = 18900\)

Đặt:

\(a = 15 x , b = 15 y \text{v}ớ\text{i}\&\text{nbsp}; gcd ⁡ \left(\right. x , y \left.\right) = 1\)

Khi đó:

\(l c m \left(\right. a , b \left.\right) = 15 x y = 1260 \Rightarrow x y = 84\)

Phân tích \(84 = 2^{2} \cdot 3 \cdot 7\)

Các cặp số tự nhiên \(\left(\right. x , y \left.\right)\) nguyên tố cùng nhau thỏa mãn \(x y = 84\) là:

• \(\left(\right. 1 , 84 \left.\right)\)
• \(\left(\right. 3 , 28 \left.\right)\)
• \(\left(\right. 4 , 21 \left.\right)\)
• \(\left(\right. 7 , 12 \left.\right)\)

Suy ra các cặp \(\left(\right. a , b \left.\right)\):

• \(\left(\right. 15 , 1260 \left.\right)\)
• \(\left(\right. 45 , 420 \left.\right)\)
• \(\left(\right. 60 , 315 \left.\right)\)
• \(\left(\right. 105 , 180 \left.\right)\)

(Các cặp hoán vị \(\left(\right. b , a \left.\right)\) cũng đều thỏa mãn.)

Kết luận:
Các cặp số tự nhiên \(a , b\) thỏa mãn đề bài là:

\(\left(\right. 15 , 1260 \left.\right) , \&\text{nbsp}; \left(\right. 45 , 420 \left.\right) , \&\text{nbsp}; \left(\right. 60 , 315 \left.\right) , \&\text{nbsp}; \left(\right. 105 , 180 \left.\right)\)

m nghĩ bọn tao ko chụp màn hình đc à

chat gì vậy

Topic 1: Describe a time when you felt nervous.

One time I felt really nervous was when I had to give a presentation in front of my class. It was my first time speaking in front of so many people, so I was very worried. Before the presentation, my hands were shaking and my heart was beating fast. I kept thinking that I might forget what I wanted to say.

When I stood in front of the class, I felt even more nervous, but I took a deep breath and tried to stay calm. After a few seconds, I focused on my notes and slowly started speaking. As I continued, I began to feel more confident. When I finished the presentation, I felt very relieved and proud of myself. This experience taught me that being nervous is normal, and I can overcome it if I try my best.

bro chọn môn học là GDCD luôn à :)?