![](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)
\(\Leftrightarrow4\left(x-3\right)=49-1=48\Leftrightarrow x-3=12\Leftrightarrow x=15\)
\(4\left(x-3\right)=7^2-1^{10}\)
\(4\left(x-3\right)=49-1\)
\(4\left(x-3\right)=48\)
\(\left(x-3\right)=48:4\)
\(x-3=12\)
\(x=15\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: x-56:4=16
nên x-14=16
hay x=30
b: \(101+\left(36-4x\right)=105\)
\(\Leftrightarrow36-4x=4\)
hay x=8
Vì a: x-56:4=16
=>x-14=16
Hay:x=30
Vì b: 101+(36−4x)=105101+(36−4x)=105
⇔36−4x=4⇔36−4x=4
Hay:x=8
Vậy x={30:8}
Nếu sai thì thui nhá,đừng chửi mình!
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,\Leftrightarrow x+9=39\Leftrightarrow x=30\\ b,\Leftrightarrow73-x=69\Leftrightarrow x=4\\ c,\Leftrightarrow x+7=38\Leftrightarrow x=31\\ d,\Leftrightarrow x+4=178\Leftrightarrow x=174\\ e,\Leftrightarrow2\left(x-51\right)=16+20=36\Leftrightarrow x-51=18\Leftrightarrow x=69\\ f,\Leftrightarrow x-19=9\Leftrightarrow x=28\\ g,\Leftrightarrow4\left(x-3\right)=49-1=48\Leftrightarrow x-3=12\Leftrightarrow x=15\)
a) 45 - ( x + 9 ) = 6
45 - x = 6 + 9
45 - x = 15
x = 45 - 15
x = 30
b) 89 - ( 73 - x ) = 20
89 - x = 20 + 73
89 - x = 93
x = 93 - 89
x = 4
c) 198 - ( x + 4 ) = 120
198 - x = 120 + 4
198 - x = 124
x = 198 - 124
x = 74
d) ( x + 7 ) - 25 = 13
x - 25 = 13 + 7
x - 25 = 20
x = 20 + 25
x = 45
e) 2 ( x - 51 ) = 2.23 + 20
2 ( x - 51 ) = 64 + 20
2 ( x - 51 ) = 84
x - 51 = 84 - 2
x - 51 = 82
x = 82 + 51
x = 133
f) 450 : ( x - 19 ) = 50
450 : x = 50 - 19
450 : x = 41
x = 450 : 41
x = 24
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\Rightarrow10-\left(x-3\right):2=49-1=48\\ \Rightarrow\left(x-3\right):2=-38\\ \Rightarrow x-3=-76\\ \Rightarrow x=-73\)
\(10-\left(x-3\right):2=7^2-1^{10}\)
\(\Rightarrow10-\left(x-3\right):2=48\)
\(\Rightarrow\left(x-3\right):2=-38\)
\(\Rightarrow x-3=-76\Rightarrow x=-73\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)\(1+2+3+4+...+x=36\)
\(\Leftrightarrow\frac{x\cdot\left(x+1\right)}{2}=36\)
\(x\left(x+1\right)=72\)
x và x+1 là 2 số tự nhiên liên tiếp mà 8 x 9 = 72
=> x = 8
b) \(1+2+3+4+...+x=820\)
\(\frac{x\cdot\left(x+1\right)}{2}=820\Leftrightarrow x\cdot\left(x+1\right)=1640\)
x và x + 1 là 2 số tự nhiên liên tiếp mà 40 x 41 = 1640
=> x = 40
c) \(2+4+6+8+...+2x=110\)
\(\frac{2x\cdot\left(2x+2\right)}{4}=110\Leftrightarrow2x\cdot\left(2x+2\right)=440\)
2x và 2x+2 là 2 số tự nhiên chẵn liên tiếp mà 20 x 22 = 440
=> 2x = 20
=> x = 10 : 2 = 10
*ta có công thức như sau 1+2+3+...+n=n x (n+1) : 2
từ đó => 1+2+3+...+n=36
suy ra n x (n+1) : 2 = 36
=> n x (n+1) = 72
ta có n x (n+1) =8x9
vì n < n+1 => n=8
*câu tiếp theo tương tự
2+4+...+2x=110
=> 2 x 1 + 2 x 2 +...+ 2 x X =110
=> 2 x ( 1 + 2 +...+X)=110
=>1 + 2 + ...+X = 110 : 2 = 55
theo như công thức trên ta có X x (X+1) =55
nếu vậy x ko có giá trị nào
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{1}{3}-\dfrac{1}{12}-\dfrac{1}{20}-\dfrac{1}{30}-\dfrac{1}{42}-\dfrac{1}{56}-\dfrac{1}{72}-\dfrac{1}{90}-\dfrac{1}{110}=x-\dfrac{5}{13}\)
\(\dfrac{1}{3}\) - \(\dfrac{1}{3.4}\) - \(\dfrac{1}{4.5}\) - \(\dfrac{1}{5.6}\) - \(\dfrac{1}{6.7}\) - \(\dfrac{1}{7.8}\)- \(\dfrac{1}{8.9}\) - \(\dfrac{1}{9.10}\) - \(\dfrac{1}{10.11}\) = \(x\) - \(\dfrac{5}{13}\)
\(\dfrac{1}{3}\) - (\(\dfrac{1}{3.4}\) + \(\dfrac{1}{4.5}\) + \(\dfrac{1}{5.6}\) + \(\dfrac{1}{6.7}\)+ \(\dfrac{1}{7.8}\) + \(\dfrac{1}{8.9}\) + \(\dfrac{1}{9.10}\) + \(\dfrac{1}{10.11}\) =\(x\)-\(\dfrac{5}{13}\)
\(\dfrac{1}{3}\) - (\(\dfrac{1}{3}\) - \(\dfrac{1}{4}\) + \(\dfrac{1}{4}\) - \(\dfrac{1}{5}\) +...+ \(\dfrac{1}{9}\) - \(\dfrac{1}{10}\) + \(\dfrac{1}{10}\) - \(\dfrac{1}{11}\)) = \(x\) - \(\dfrac{5}{13}\)
\(\dfrac{1}{3}\) - (\(\dfrac{1}{3}\) - \(\dfrac{1}{11}\)) = \(x\) - \(\dfrac{5}{13}\)
\(\dfrac{1}{3}\) - \(\dfrac{1}{3}\) + \(\dfrac{1}{11}\) = \(x\) - \(\dfrac{5}{13}\)
\(x-\dfrac{5}{13}=\dfrac{1}{11}\)
\(x\) = \(\dfrac{1}{11}\) + \(\dfrac{5}{13}\)
\(x\) = \(\dfrac{68}{143}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
- dễ mà VD : tách 1/30 thành 1/5.6 + 1/6.7 + 1/7.8 + 1/8.9 + 1/9.10 + 1/10.11 +1/11.12 - x =2/3
4 . ( x - 3 ) = 72 - 110
4 . ( x - 3 ) = 49 - 1
4 . ( x - 3 ) = 48
x - 3 = 48 : 4
x - 3 = 12
x = 12 + 3
x = 15
4 (x - 3) = 72 - 110
4 (x - 3) = 49 - 1
4 (x - 3) = 48
=> x - 3 = 48 : 4
x - 3 = 12
x = 12 + 3
x = 15
~ Hok T ~