Giúp mk nhanh vs ạ mk tik cho ;)
Tam giác ABC vuông tại A có 3AB= 2BC và AC =5A
Tính độ dài AB?
K
Khách
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D
15
M
6
PD
1
23 tháng 7 2018
Ta có : ( 5n + 2 )2 - 4 = ( 5n + 2 ) . ( 5n + 2 ) - 4 .
= 25n2 + 20n + 4 - 4 .
= 25n2 + 20n .
= 5 . ( 5n2 + 4n ) .
Do đó : ( 5n + 2 )2 - 4 ⋮ 5 .
Vậy bài toán được chúng minh .
VT
2
13 tháng 3 2018
\(xy+x^2+x+y=\)\(3\)
\(x\left(y+x\right)+\left(x+y\right)=3\)
\(\left(x+1\right)\left(y+x\right)=3\)
Mà Ư(3)={-1;1;-3;3}
Ta có bảng sau:
| \(y+x\) | \(-1\) | \(-3\) | \(1\) | \(3\) |
| \(x+1\) | \(-3\) | \(-1\) | \(3\) | \(1\) |
| \(x\) | \(-4\) | \(-2\) | \(2\) | \(0\) |
| \(y\) | \(3\) | \(-1\) | \(-1\) | \(3\) |
Vậy các cặp (x,y)là (-4;3),(-2;-1),(2;-1);(0;3)
tk mk nha
S
31 tháng 8 2018
Write about the kind of book you best
I am usually in habit of reading books. Addition to books that offer me much useful information,I also comic book. I am in fond of it for some following reasons.
To begin with, Comic books bring me a great deal of relaxation. One of them is Doremon story, which tells many funny short stories about 2 main characters, Doremon and Nobita,Who are close friends. The author of that comic creats so many amusing situations among characters that I can”t help laughing. It”s actually a hard-to-put-down book. It attracts not only children but also adults as me.
Another good point of it I want to mention about is creative imagination. I mean children need to have imaginative mindset, which helps them be more active in life.
By and large, comic book is worth reading after hard work. It is nice for everyone.
S
31 tháng 8 2018
Write about the kind of book you best
I am usually in habit of reading books. Addition to books that offer me much useful information,I also comic book. I am in fond of it for some following reasons.
To begin with, Comic books bring me a great deal of relaxation. One of them is Doremon story, which tells many funny short stories about 2 main characters, Doremon and Nobita,Who are close friends. The author of that comic creats so many amusing situations among characters that I can”t help laughing. It”s actually a hard-to-put-down book. It attracts not only children but also adults as me.
Another good point of it I want to mention about is creative imagination. I mean children need to have imaginative mindset, which helps them be more active in life.
By and large, comic book is worth reading after hard work. It is nice for everyone.
VH
31 tháng 5 2018
https://www.google.com.vn/search?q=%E1%BA%A3nh+chibi+d%E1%BB%85+th%C6%B0%C6%A1ng+v%C3%A0+%C4%91%E1%BA%B9p&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjd6d2Sga_bAhXEW5QKHWrjDZ0QsAQIIw&biw=1366&bih=663
* Link đó !
D
8
* Sửa '' 5A '' => '' 5a ''
\(\text{Theo đề ra:}\)\(3AB=2BC\)
\(\Rightarrow BC=\frac{3}{2}AB\)
\(\text{Áp dụng định lý Py-ta-go, ta có: }\)
\(AB^2+AC^2=BC^2\)
\(\Rightarrow AB^2+25a^2=\frac{9}{4}AB^2\)
\(\Rightarrow25a^2=\frac{5}{4}AB^2\)
\(\Rightarrow AB^2=20a^2\)
\(\Rightarrow AB=2\sqrt{5a}\)