![](https://rs.olm.vn/images/avt/0.png?1311)
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có : 1 + 2 + 3 + .... + x = yyy \(\left(x;y\inℕ^∗\right)\)
=> x(x + 1)/2 = y.111
=> x(x + 1) = y.222
Vì \(0< y< 10\left(y\inℕ^∗\right)\)
\(\Rightarrow y\in\left\{1;2;3;4;...9\right\}\Leftrightarrow222.y\in\left\{222;444;666;888;....;1998\right\}\)
Nếu y = 1 => 222y = 222
=> x(x + 1) = 222 => \(x\in\varnothing\)
Nếu y = 2 => 222y = 444
=> x(x + 1) = 444 => \(x\in\varnothing\)
Nếu y = 3 => 222y = 666
=> x(x + 1) = 666 => \(x\in\varnothing\)
Nếu y = 4 => 222y = 888
=> x(x + 1) = 888 => \(x\in\varnothing\)
Nếu y = 5 => 222y = 1110
=> x(x + 1) = 1110 => \(x\in\varnothing\)
Nếu y = 6 => 222y = 1322
=> x(x + 1) = 666 = 36.37 => x = 37 (tm)
Nếu y = 7 => 222y = 1554
=> x(x + 1) = 1554 => \(x\in\varnothing\)
Nếu y = 8 => 222y = 1776
=> x(x + 1) = 1776 => \(x\in\varnothing\)
Nếu y = 9 => 222y = 1998
=> x(x + 1) = 1998 => \(x\in\varnothing\)
Vậy x = 36 ; y = 6
Ta có: 1+2+3+...+x=yyy
=>x(x+1)/2=111y
=>x(x+1)=222y
Vì y là chữ số nên 0 < y < 10
Suy ra: x,(x+1) thuộc 222y={222,444,666,888,...,1998}
Lại có x(x+1) là tích 2 số tự nhiên liên tiếp
=>x(x+1)=1332
=>x=36,x+1=1332(TM)
Vì x(x+1)=222y
=>222y=1332
=>y=6
Vậy: x=36, y=6
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a: Ta có: \(48751-\left(10425+y\right)=3828:12\)
\(\Leftrightarrow y+10425=48751-319=48432\)
hay y=38007
b: Ta có: \(\left(2367-y\right)-\left(2^{10}-7\right)=15^2-20\)
\(\Leftrightarrow2367-y=1222\)
hay y=1145
Bài 2:
Ta có: \(8\cdot6+288:\left(x-3\right)^2=50\)
\(\Leftrightarrow288:\left(x-3\right)^2=2\)
\(\Leftrightarrow\left(x-3\right)^2=144\)
\(\Leftrightarrow\left[{}\begin{matrix}x-3=12\\x-3=-12\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=15\\x=-9\end{matrix}\right.\)