![](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)
x3 = 125
x3 = 53
x = 5
2x = 128
2x = 27
x = 7
127 < 5x < 630
127 < 625 < 630
127 < 54 < 630
x = 4
![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=5+3^2+3^3+...+3^{2018}\)
\(3A=15+3^3+3^4+...+3^{2019}\)
\(3A-A=\left(15+3^3+3^4+...+3^{2019}\right)-\left(5+3^2+3^3+...+3^{2018}\right)\)
\(2A=1+3^{2019}\)
\(2A-1=3^{2019}\)
Suy ra \(n=2019\).
![](https://rs.olm.vn/images/avt/0.png?1311)
33.(X-26)=34
=X-26=34:33
=X-26=31
=X-26=3
=X =3+26
=X =67
HT
![](https://rs.olm.vn/images/avt/0.png?1311)
(x-15) : 2 = 1002
(x-15) = 1002 . 2
x-15 = 2004
x = 2004 + 15
x = 2019
3.x - 33 = 32020 : 32019
3.x - 33 = 32020-2019
3.x - 33 = 3
3x = 3 + 33
3.x = 36
x = 36 : 3
x = 12
tk cj nha
+)\(\left(x-15\right):2=1002\)
\(x-15=1002.2\)
\(x-15=2004\)
\(x=2004+15\)
\(x=2019\)
+)\(3x-33=3^{2020}:3^{2019}\)
\(3x-33=3\)
\(3x=33+3\)
\(3x=36\)
\(x=36:3\)
\(x=12\)
Chúc bạn học tốt!
![](https://rs.olm.vn/images/avt/0.png?1311)
S*2=1+1/2+1/2mũ2+1/2mũ3+...+1/2mũ19
S*2-S=1-1/2mũ20
S=1-1/2mũ20<1
Vậy bài toán được chứng minh
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(2xy+2x-y=8\)
\(\Rightarrow\ 2x\left(y+1\right)-\left(y+1\right)=7\)
\(\Leftrightarrow\left(2x-1\right)\left(y+1\right)=7\)
\(\Rightarrow\left[\begin{matrix}\begin{cases}2x-1=-7\\y+1=-1\end{cases}\\\begin{cases}2x-1=-1\\y+1=-7\end{cases}\end{matrix}\right.\left[\begin{matrix}\begin{cases}2x-1=7\\y+1=1\end{cases}\\\begin{cases}2x-1=1\\y+1=7\end{cases}\end{matrix}\right.\) \(\Rightarrow\left[\begin{matrix}\left[\begin{matrix}\begin{cases}x=4\\y=0\end{cases}\end{matrix}\right.\\\left[\begin{matrix}\begin{cases}x=1\\y=6\end{cases}\\\left[\begin{matrix}\begin{cases}x=-3\\y=-2\end{cases}\\\begin{cases}x=0\\y=-8\end{cases}\end{matrix}\right.\end{matrix}\right.\end{matrix}\right.\)
c)\(x^2+xy+x+y=2\)
\(\Leftrightarrow x\left(x+1\right)+y\left(x+1\right)=2\)
\(\Leftrightarrow\left(x+y\right)\left(x+1\right)=2\)
\(\Rightarrow\left[\begin{matrix}\left[\begin{matrix}\begin{cases}x+y=2\\x+1=1\end{cases}\\\begin{cases}x+y=1\\x+1=2\end{cases}\end{matrix}\right.\\\left[\begin{matrix}\begin{cases}x+y=-2\\x+1=-1\end{cases}\\\begin{cases}x+y=-1\\x+1=-2\end{cases}\end{matrix}\right.\end{matrix}\right.\) \(\Rightarrow\left[\begin{matrix}\left[\begin{matrix}\begin{cases}x=0\\y=2\end{cases}\\\begin{cases}x=1\\y=0\end{cases}\end{matrix}\right.\\\left[\begin{matrix}\begin{cases}x=-2\\y=0\end{cases}\\\begin{cases}x=-3\\y=2\end{cases}\end{matrix}\right.\end{matrix}\right.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
600 : {[( 100 - 23. 5 ) : 10 ] . 2 }
= 600 : {[( 100 - 8.5 ) : 10 ] . 2 }
= 600 : {[( 100 - 40 ):10 ] . 2 }
= 600 : {[ 60 :10 ] . 2 }
= 600 : { 6.2 }
= 600 : 12
= 50
( 7x - 23 ) : 5 = 43
( 7x - 23 ) : 5 = 64
7x - 23 = 64x5
7x - 23 = 320
7x = 320 + 23
7x = 343
x = 343 : 7
x = 49
( 35 - x ) . 326= 328
( 35 - x ) = 328 : 326
35 - x = 32
35 - x = 9
X = 35 -9
X = 26