Tìm các số hữu tỉ a,b sao cho \(\left(a-2\right).\sqrt{2=b+1}\)
Các bạn giúp mk nha. Mk đang cần gấp.Cảm ơn các bạn nhiều
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1 tháng 12 2019
<=>(x-4)(x+1)(x-4)<0
<=> (x-4)^2(x+1)<0 mà (x-4)^2>=0
<=> x+1<0<=> x<-1
1 tháng 12 2019
sr bn mình viết sai đề phải là\(\left(x-2\right)^2\left(x+1\right)\left(x-4\right)< 0\)
16 tháng 8 2018
ta có \(\left(1-\frac{1}{2010}.\right).\left(1-\frac{2}{2010}\right)....\left(1-\frac{2010}{2010}\right).\left(1-\frac{2011}{2010}\right)\)\(\left(1-\frac{1}{2010}\right).\left(1-\frac{2}{2010}\right).......0.\left(1-\frac{2011}{2010}\right)=0\)
24 tháng 7 2016
hello, my name is .(tên bạn).. Today, i'll tell you about my class recess. The recess lasts for 15 minutes. At recess, my class has a lot of activities. For example, some boys play soccer, play marbles and play tag while girls skip rope. For me, I usually study under the tree. At recess, I like sitting around and reading books reading stories helps I feel more relaxed. The recess of my class is fun and exciting. I love the recess very much because it helps me relax after stressful hours.
TN
24 tháng 7 2016
Of course, recess time is the most enjoyable time in school after learning hard from the first period. There are two recess time in my school. These two recess time are essential for us to unwind and to fill up growling stomach.As soon as the school bell rings for recess, all students perk up. School work burden is forgotten, at least for a while. All the sorrows of being scolded and getting bad marks areforgotten. There will be a stampede towards the canteen. The junior students particularly are chattering in a jovial mood. However, there will be some students going for meetings, going to the library and the washrooms to refresh themselves. Only a minority stays in class.
The benches in the canteen at recess time are never unoccupied. Some of them even have to put their things on the tables in the canteen to ensure a seat. An advantage in size could certainly be a great help here. Every stall is always crowded with students. Some of the hawkers are not able to serve thecustomers at once. It is also hard to walk through the rowdy crowd in the canteen. Believe me, you will experience beingpushed from one side to another.
Some hearty laugh and chat are always heard. Though recess time may seem short, it is the time for students to share endless gossip with their peers. Very often you will hear the hawkers' screaming at the top of their voices to control the students from pushing and shoving. Some prefects are on duty to control these "uncivilised people". Unfortunately, it makes not much difference. And of course, some impatient students willscream out: "Quick, Auntie, quick, the bell for going back to class will ring soon."
Meantime in the library, several students are busy searching and skimming the books for extra reading and setting information for their assignments. Several students can be seen engrossed in the daily news with their best friends. The scene in the library during recess time is quiet and full of disciplinealthough some quiet chat can be heard.
Some hard-working student or I should say bookworm will stay in their own class to finish their homework or revise. While some students are seen carrying out their cleanliness duty. You may see of a couple of girls diligently mopping the windows, sweeping the floor and cleaning the blackboard. It is certainlypleasant to study in a spick and span class room.
Some of the students will also enjoy walking around the passageways in front of the classrooms or in the park chatting with their peers. Some younger students who have not 'tasted' school work pressure play hide and seek with their friends. While the older ones are deep in thought in some corners. A few are seen trying to solve additional Maths or Physics problems. Certainly, one will also see some pupils running here and therealong the passageway while the others just loiter around.
In the wash rooms, you may find some students washing their faces to refresh themselves after studying hard since morning. Some even have to stand in a queue for a while to use the toilets. The toilets are never unoccupied. Each class has is specified for its own toilet.
All in all, I can say that the scene in my school during recess time is one of noise and many students. Students enjoy their own activities during this time. I, myself, enjoy every moment of recess time very much.
2 tháng 10 2017
Phương Bùi Mai
Ta có : a - b = a : b = 2(a + b)
Ta có : a - b = 2(a + b)
=> a - b = 2a + 2b
=> a - 2a = b + 2b
=> -a = 3b
=> a = -3b (*)
Lại có : a - b = a : b
b(a - b) = a (**)
Từ (*) (**) Ta có : -3b = b(a - b)
=> a - b = -3
Thay a - b = -3 , a = -3b vào a - b ta có :
-3b - b = -3
-4b = -3
b = 3/4
=> a = -3.3/4 =-9/4
Vậy a = -9/4, b = 3/4
Ta có : \(\left(a-2\right).\sqrt{2}=b+1\)
Từ giả thiết a,b là các số hữu tỉ nên ta có VT là một số vô tỉ, vế phải là một số hữu tỉ. Do đó ta cần tìm a để VT là một số hữu tỉ. Nhận thấy chỉ có a = 2 thỏa mãn . Suy ra b = -1
Vậy (a;b) = (2;-1)
dấu căn j mà ngộ thế kia be cả dấu =