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25 tháng 3 2020

x=7

y=3

chúc bạn học tốt

AH
Akai Haruma
Giáo viên
12 tháng 8 2023

Lời giải:

a. Với $n$ nguyên khác -3, để $B$ nguyên thì:

$2n+9\vdots n+3$

$\Rightarrow 2(n+3)+3\vdots n+3$

$\Rightarrow 3\vdots n+3$

$\Rightarrow n+3\in\left\{\pm 1; \pm 3\right\}$

$\Rightarrow n\in\left\{-2; -4; 0; -6\right\}$

b. 

$B=\frac{2n+9}{n+3}=\frac{2(n+3)+3}{n+3}=2+\frac{3}{n+3}$

Để $B_{\max}$ thì $\frac{3}{n+3}$ max

Điều này đạt được khi $n+3$ là số nguyên dương nhỏ nhất

Tức là $n+3=1$

$\Leftrightarrow n=-2$

c. Để $B$ min thì $\frac{3}{n+3}$ min

Điều này đạt được khi $n+3$ là số nguyên âm lớn nhất 

Tức là $n+3=-1$

$\Leftrightarrow n=-4$

4 tháng 9 2021

9. I spend about two hours walking to school.

10. It took Susan an hour to prepare her report.

11. I spent three months learning piano.

12. It took Adam 30 minutes to read a book everyday.

13. It often takes her 20 minutes to review her lesson before class.

4 tháng 9 2021

9 l spend about two hours walking to school 

10 it took susan an hour to prepare her report 

11 l spent three months learning piano 

12 it took adam 30 minutes to read a book everyday 

13 it often takes her 20 minutes to review her lesson before class

15 tháng 10 2016

ai giúp mik với Ôn tập toán 7

cảm ơn các bạn trước

16 tháng 10 2016

Chịu thôi

16 tháng 10 2016

Chịu thôi

16 tháng 10 2016

tổng ko bao giờ bé hơn các số hạng đc nên chắc đề bài sai vì nếu cả x và y đều bằng 0 thì 200 vẫn > 100 mà 

16 tháng 4 2018

Spring is the beginning of a year. Around this time, the climate is still cold and humid. There are still some small drizzles outside but they seem not be able to stop the hundreds of colorful flowers blooming. Peach blossoms, apricot blossoms and lime trees are the most favorite plants for the Lunar New Year. Apricot blossom is yellow, peach blossom is pink, these color brighten up the sky. Spring arriving means that with New Year is coming. At this moment, everyone's heart is throbbing. The roads are filled with vehicles, everyone is happy, they go shopping to prepare for Tet holiday such as buying trees, clothes, foods.Traditionally, all of houses hang red sentences in front of the house, plant trees, wrap green cake to eat with melon onion. This is a characteris that only Vietnam has, leaves impression on the tourists. Children are especially happy to wear new clothes and receive red envelopes, are taken to visit the relatives. For me, the spring is so special, it carries so much love and happiness.
bạn thamkhaor nha

16 tháng 4 2018

Spring has long been called the season of the festivals. Especially in some Asia countries including Vietnam, at this time there are many big and small festivals taken place all over the country. First of all, Tet is the most important event of our country. It just for a week but is well-received and well prepared. Everyone is looking forward to Tet, they go shopping for the New Year from December twenty one, prepare some items such as bonsai, candy, clothes, ..... This is a chance for them to remember their ancestors, spend time together, give each other best wishes, ... Besides Tet, there are many other festivals in the spring. Many people tend go to pagodas, temples, find the ancient land to pray for the family healthy and peaceful. Some families book themselves a short vacation, go to the famous sightseeing tours, recharge energy for a new year. Maybe spring makes people excited and happy because it has so many festivals. Thus, when talk about spring, people often think of joy, excitement.
 

15 tháng 7 2018

pls mik đang rất gấp

3 tháng 1 2022

2xy - 3x + 5y=4

2x(y-1) + 5y = 4

2x(y-1) + 5y - 5 = 4 - 5

2x(y-1) - 1(y-1) = -1

(2x-1)(y-1) = -1

Ta thấy -1= (-1).1 => Ta có bảng sau:

2x-1-11
y-11-1
x01
y20

Như vậy, ta có 2 trường hợp (x;y) thỏa mãn yêu cầu đề bài là ( 0;2 ) ; ( 1;0 )

Hok tốt~

27 tháng 7 2016

Tự lm đ