Tính
B,2x=7y và x.y=42
Ai Làm Nhanh Mk Sẽ Tích Cho Nhé cảm ơn nhiều
Mk Đang cần gấp ạ
K
Khách
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TH
Thầy Hùng Olm
Manager
VIP
13 tháng 7 2023
\(E=\dfrac{3}{1x5}+\dfrac{3}{5x9}+...+\dfrac{3}{121x125}\)
\(\dfrac{4}{3}xE=1-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{9}+...+\dfrac{1}{121}-\dfrac{1}{125}\)
\(\dfrac{4}{3}xE=1-\dfrac{1}{125}\)
\(E=\dfrac{124}{125}x\dfrac{3}{4}=\dfrac{93}{125}\)
NA
28 tháng 9 2018
a) 5y = 72
=> y = 72/5
2x = 3y
<=> 2x = 3 . 72/5
<=> 2x = 216 / 5
<=> x =108/5
3x - 7y + 5z = -30
<=> 3 . 108/5 - 7. 72/5 + 5z = - 30
<=> 324/5 - 504/5 +5z = -30
<=> 5z = 6
<=> x = 6/5
NA
28 tháng 9 2018
câu a đoạn cuối z = 6/5 nha
b) x : y : z = 5 : 3 :4
\(\Leftrightarrow\frac{x}{5}=\frac{y}{3}=\frac{z}{4}\Leftrightarrow\frac{x}{5}=\frac{2y}{6}=\frac{z}{4}\)
Áp dụng t/c dãy tỉ số = nhau , ta có
\(\frac{x}{5}=\frac{2y}{6}=\frac{z}{4}=\frac{x+2y-z}{5+6-4}=\frac{-121}{7}\)
=> x =-605/ 7
=> y = -363 / 7
=> z = -484 / 7
5 tháng 11 2021
mọi người ơi, đây có phải là đáp án đúng của bài 1 không ạ, nếu đúng thì giúp em viết ra giống như trên với ạ, em nhìn được nhưng 1 số chỗ không rõ lắm, huhu
NV
Nguyễn Việt Lâm
Giáo viên
7 tháng 2 2021
\(S_{ABC}=\dfrac{1}{2}AB.AC.sinA\)
\(\Rightarrow AB=\dfrac{2S_{ABC}}{AC.sinA}=\dfrac{10\sqrt{3}}{3}\)
Áp dụng định lý hàm cos:
\(BC=\sqrt{AB^2+AC^2-2AB.AC.cosA}=5,89\)
\(\Rightarrow AH=\dfrac{2S}{BC}=6,79\)
8 tháng 8 2018
\(\left|x\right|=2\Rightarrow\orbr{\begin{cases}x=2\\x=-2\end{cases}}\)
Khi x = 2 thì \(5x^2-2x+3x-1=5.2^2-2.2+3.2-1=20-4+6-1=21\)
Khi x = -2 thì \(5x^2-2x+3x-1=5.\left(-2\right)^2-2.\left(-2\right)+3.\left(-2\right)-1\)
\(=20+4-6-1=17\)
TD
3 tháng 2 2022
Tham khảo
There is a famous animated film that I think everyone of us has seen at least once, and it is Tom and Jerry. Almost everyone is aware of the story between the miserable Tom and the mischievous mouse Jerry, and it also was part of my childhood memories. The film is about a life under the same roof between two enemies Tom and Jerry, and of course cat and mouse are always hard to get along with. Tom's owner is very afraid mouse, so she always asks Tom to catch the little mouse living in a cave that he digs on the wall. Tom is a quite lazy cat, and he often has to chase Tom so that he is not scolded by his owner or in exchange for a good meal. Sometimes, Jerry also makes mischievous jokes to tease Tom such as pull out his hair or steal his milk. Another character in the movie is the dog Spike, and he does not seem to like Tom at all. In the chasing scenes of the two main characters, they sometimes run to the garden - Spike's residence - and disturb his sleep. Most of the time, Tom would be the one who suffers Spike's anger while Jerry is having a big laugh. The plot is simple but the film Tom and Jerry always attracts a lot of audiences of all ages thanks to the lovely characters and funny circumstances. Although many years have gone by, the television channels have often displayed this film, and this is the indispensable spiritual food children.
TP
3 tháng 2 2022
Refer
Write about your favourite movie
Today I’d like to talk to you about Harry Porter which is one of my favourite films. It was a fiction film telling a story about people in the wizarding world. The central character was Harry Porter, who used to be an orphan in the normal world before discovering that he was a wizard. Afterwards, he went to a special school called Howard where taught him necessary skills to succeed in wizarding world. He also had to deal with challenges in terms of study, friendship, love and even the fight against dark power.
Harry Porter was recommended as a masterpiece that making me feel curious about it. Moreover, I had read the original novel before, and I really can’t put it down. So I guess the film would be as attractive as the book.
I think the most important reason why I enjoyed this film was that it made me feel adventurous. It was really a fantastic film.
Write about your favourite book
Favorite book and then the series "Doraemon" by Fujiko Fujio. The series told the cat from the future into the past Doremon same friends and help Nobita in the security context miracle. The main character is Doremon with your group Nobita, Shizuka, Xeko, Chaien. Extremely interesting story, engage the reader with the hilarious, witty, and full of magic. But it is also part of suspense through risky adventure of your group. The series is divided into two categories: short stories and novels. I enjoyed the long story, it's about the adventures in a strange land or through time times exciting but dangerous, and the group must go through many difficulties and from there we saw noble friendship bunch of kids. When I read the story I kept imagining myself as the character in that book that I could not put down. And I learned a lot from it especially friendships! If you have not read it try to read offline sure you will like it.
29 tháng 6 2023
a: Xét ΔEAD và ΔECG có
góc EAD=góc ECG
góc AED=góc CEG
=>ΔEAD đồng dạng với ΔECG
=>AD/CG=ED/EG
=>AD*EG=ED*CG
b: Xét ΔHEG và ΔHCB có
góc HEG=góc HCB
góc EHG=góc CHB
=>ΔHEG đồng dạng với ΔHCB
=>HE/HC=HG/HB
Xét ΔHAB và ΔHCG có
góc HAB=góc HCG
góc AHB=góc CHG
=>ΔHAB đồng dạng với ΔHCG
=>HA/HC=HB/HG
=>HC/HA=HG/HB
=>HC/HA=HE/HC
=>HC^2=HA*HE
c: HI//BA
=>HI/BA=CH/CA=CI/CB
HI//EG
=>HI/EG=BI/BC
HI/BA=CI/CB
HI/BA+HI/EG=BI/BC+CI/BC=1
=>HI(1/BA+1/EG)=1
=>1/BA+1/EG=1/HI
18 tháng 9 2023
Mình nhớ câu này mình đã giải rồi, không biết vì lý do gì mà bạn lại xóa đi vậy nhỉ? Và nếu CH đã đăng, yêu cầu bạn không đăng lại lần thứ 2!
Vì 2x = 7y \(\Rightarrow\) \(\frac{x}{7}\) =\(\frac{y}{2}\)
Đặt \(\frac{x}{7}\)=\(\frac{y}{2}\) =k \(\Rightarrow\) \(\hept{\begin{cases}x=7k\\y=2k\end{cases}}\)
mà x . y=42
\(\Leftrightarrow\)7k .2k =42
\(\Leftrightarrow\)14k2 =42
\(\Leftrightarrow\)k= \(\sqrt{3}\)
\(\Rightarrow\)\(\hept{\begin{cases}x=7\sqrt{3}\\y=2\sqrt{3}\end{cases}}\)