Giúp mình tí :
x+(x+1)+(x+2)+......+(x+100)=5051
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( x + 1 ) + ( x + 2 ) + ( x + 3 ) = 100
=> 3x + 6 = 100
=> 3x = 94
=> x = \(\frac{94}{3}\)
\(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)=100\)
\(\Rightarrow3x+6=100\)
\(\Rightarrow3x=94\)
\(\Rightarrow x=\frac{94}{3}\)
Vậy...
1/5051 +(-2/5051)+3/5051+(-4/5051)+...+99/5051+(-100/5051)
\(=\frac{\left(1-2\right)+\left(3-4\right)+...+\left(99-100\right)}{5051}\)
\(=\frac{-1+\left(-1\right)+..+\left(-1\right)}{5051}\) (có 50 số -1)
\(=\frac{\left(-1\right).50}{5051}=\frac{-50}{5051}\)
A. \(\left(x+1\right)+\left(x+2\right)+......+\left(x+100\right)=5750\)
\(x+1+x+2+....+x+100=5750\)
\(100x+\left(1+2+3+.......+100\right)=5750\)
\(100x+5050=5750\)
\(100x=700\)
\(x=700:100=7\)
B. x+(1+2+......+100) = 2000
x + 5050 = 2000
x = 2000 - 5050
x= -3050
C. ( x-1 )+(x-2)+......+( x - 100 ) = 50
x-1+x-2+.........+x-100 = 50
100x + ( -1-2-........-100 ) = 50
100x + ( - 5050 ) = 50
100x = 50 + 5050
100 x = 5100
x = 5100 : 100
x = 51
A . \(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+...+\left(x+100\right)=5750\)
\(\left(x+x+x+...+x\right)+\left(1+2+3+...+100\right)=5750\)
\(100x+5050=5750\)
\(100x=5750-5050\)
\(100x=700\)
\(\Rightarrow x=\frac{700}{100}=7\)
B. \(x+\left(1+2+3+4+5+....+100\right)=2000\)
\(x+\frac{\left(100+1\right).100}{2}=2000\)
\(x+5050=2000\)
\(\Rightarrow x=2000-5050=-3050\)
C. \(\left(x-1\right)+\left(x-2\right)+\left(x-3\right)+....+\left(x-100\right)=50\)
\(\left(x+x+x+...+x\right)-\left(1+2+3+...+100\right)=50\)
\(100x-5050=50\)
\(100x=5100\)
\(\Rightarrow x=\frac{5100}{100}=51\)
a, ( x + 5 ).( y - 3 ) = 15 = 3 . 5 = 1 . 15 = ( -1) . ( - 15) = ( - 3) . ( -5)
x+5 | 3 | 5 | 1 | 15 | -1 | -15 | -3 | -5 | |||||||
y-3 | 5 | 3 | 15 | 1 | -15 | -1 | -5 | -3 | |||||||
x | -2 | 0 | -4 | 10 | -6 | -20 | -8 | -10 | |||||||
y | 8 | 6 | 18 | 4 | -12 | 2 | -2 | 0 |
Ta có :
\(\frac{1}{8}< \frac{x}{12}< \frac{1}{4}\)
\(\Leftrightarrow\)\(\frac{3}{24}< \frac{2x}{24}< \frac{6}{24}\)
\(\Leftrightarrow\)\(3< 2x< 6\)
\(\Leftrightarrow\)\(2x\in\left\{4;5\right\}\)
Loại \(x=5\)vì \(x\in Z\)
Do đó :
\(2x=4\Rightarrow x=\frac{4}{2}=2\)
Vậy \(x=2\)
\(\frac{1}{8}< \frac{x}{12}< \frac{1}{4}\Rightarrow\frac{1.3}{8.3}< \frac{x.2}{12.2}< \frac{1.6}{4.6}\)
\(\Rightarrow\frac{3}{24}< \frac{2x}{24}< \frac{6}{24}\)
\(\Rightarrow\frac{2x}{24}=\frac{4}{24}\)hoặc \(=\frac{5}{24}\)
mà \(\frac{2x}{24}=\frac{4}{24}\Rightarrow2x=\frac{4.24}{24}=4\Rightarrow x=\frac{4}{2}=2\)( luôn đúng)
=> x = 2 ( đpcm)
\(x+\left(x+1\right)+\left(x+2\right)+...+\left(x+100\right)=5051\)
\(\Rightarrow x.101+\left(1+2+...+100\right)=5051\)
\(\Rightarrow x.101+5050=5051\)
\(\Rightarrow x.101=5051-5050\)
\(\Rightarrow x.101=1\)
\(\Rightarrow x=1:101\)
\(\Rightarrow x=1\)
Vậy \(x=1\)
bn làm sai rồi