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a) 6,25 x X + 3,75 x X = 30
X x ( 6,25 + 3,75) = 30
X x 10 = 30
X = 30 : 10
X = 3
=> 6,25 x 3 + 3,75 x 3 = 30
b) \(\frac{4}{X}=\frac{1}{7}\)
\(X=4\div1\times7\)
\(X=28\)
\(=>\frac{4}{28}=\frac{1}{7}\)
c) 5 x X + 14 - 3 x X = 30
X x ( 5 - 3 ) = 30 - 14
X x 2 = 16
X = 16 : 2
X = 8
=> 5 x 8 + 14 - 3 x 8 = 30
Mọi người ơi nhé!
Chúc mọi người học tập tốt như củ cà rốt ! hihi ^-^
Thank you very much!
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a) x + 3.x + 5.x + ... + 2009. x = 2010.1005
\(x\times\left(1+3+5+...+2009\right)=2010\times1005\)
\(x\times\left[\left(1+2009\right)\times1005:2\right]=2010\times1005\)
\(x\times2010\times1005\times\frac{1}{2}=2010\times1005\)
\(\Rightarrow x\times\frac{1}{2}=2010\times1005:\left(2010\times1005\right)\)
\(x\times\frac{1}{2}=1\)
x = 2
b) x + (x+1) + (x+2) +...+ (x+30) = 620
x. 31 + ( 1+2+...+30) = 620
x.31 + [ ( 30+1).30:2) = 620
x.31 + 465 = 620
x.31 = 620 - 465
x.31 = 155
x = 155 : 31
x = 5
a) x+3.x+5.x+.....+2009.x = 2010.1005
=> x.(1+3+5+....+2009) = 2010.1005
=> x.1010025 = 2020050
=> x = 2
Vậy x = 2
b) x+(x+1)+(x+2)+....+(x+30) = 620
=> (x+x+x+...+x)+(1+2+3+...+30) = 620
=> 31x + 465 = 620
=> 31x = 155
=> x = 5
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\(a,30+X=120:5+27\\ 30+X=24+27\\ 30+X=51\\ X=51-30=21\\ ---\\ b,40-3\times X=13\\ 3\times X=40-13=27\\ X=\dfrac{27}{3}=9\\ ---\\ 2\times X-8=16\\ 2\times X=16+8\\ 2\times X=24\\ X=\dfrac{24}{2}=12\\ \\---\\ \dfrac{1}{2}\times X-\dfrac{1}{3}=\dfrac{1}{4}\\ \dfrac{1}{2}\times X=\dfrac{1}{4}+\dfrac{1}{3}=\dfrac{7}{12}\\ X=\dfrac{7}{12}:\dfrac{1}{2}=\dfrac{7}{6}\)
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1) (x - 35) - 120 = 0
x - 35 = 120
x = 120 + 35
x = 155
2) 310 - (118 - x) = 217
118 - x = 310 - 217
118 - x = 93
x = 118 - 93
x = 25
3) 156 - (x + 61) = 82
x + 61 = 156 - 82
x + 61 = 74
x = 74 - 61
x = 13
4) 814 - (x - 305) = 712
x - 305 = 814 - 712
x - 305 = 102
x = 102 + 305 = 407
5) 100 - 7 - (x - 5) = 58
x - 5 = 93 - 58
x - 5 = 35
x = 35 + 5 = 40
6) 12(x - 1) : 3 = 43 + 23
4(x - 1) = 72
x - 1 = 18
x = 18 + 1 = 19
7) 24 + 5x = 75 : 73
24 + 5x = 49
5x = 25
x = 25 : 5 = 5
8) 5(x - 1) : 3 = 43 + 23
\(\dfrac{5}{3}\left(x-1\right)=72\)
x - 1 = \(\dfrac{216}{5}\)
x = 221/5
9) 5(x - 4)2 - 7 = 13
5(x - 4)2 = 20
(x - 4)2 = 4
\(\Rightarrow\left[{}\begin{matrix}x-4=2\\x-4=-2\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=6\\x=2\end{matrix}\right.\)
10) (x + 1) + (x + 2) + ... + (x + 30) = 795
=> (x + x + x + ... + x) + (1 + 2 + 3 +...+ 30) = 795 (1)
Đặt A = 1 + 2 + 3 +...+ 30
Số số hạng trong A là: (30 - 1) : 1 + 1 = 30 (số)
Tổng A bằng : (30 + 1).30 : 2 =465
Thay A = 465 vào (1) , ta được:
30x + 465 = 795
=> 30x =330
=> x =11
1: =>x-35=120
=>x=120+35=155
2: =>118-x=310-217=93
=>x=118-93=25
3: =>x+61=156-82=74
=>x=74-61=13
4: =>x-305=814-712=102
=>x=102+305=407
5: =>93-(x-5)=58
=>x-5=35
=>x=40
6: =>4(x-1)=64+8=72
=>x-1=18
=>x=19
7: =>5x+24=49
=>5x=25
=>x=5
8: =>5(x-1):3=4^3+2^3=64+8=72
=>5(x-1)=216
=>x-1=216/5
=>x=221/5
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a) 2009<5*x -3 <2013
=> 2012<5*x<2016
=> 402<x<404=>x=403
b) 5*x +1+2+3+....+30=525
=> 5*x +31*30/2=525
=>5*x=60
=>x=12
5x-3=2010
5x-3=2011
5x-3=2012
5x=2007
5x=2008
5x=2009
ko có x thỏa mãn là số tự nhiên
b, 5x+ 465=525
5x=525-465
5x=60
x=60:5
x=14
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\(\left(\dfrac{4}{5}:\dfrac{6}{5}+\dfrac{1}{5}:\dfrac{1}{x}\right)\times30-26=54\)
\(\left(\dfrac{4}{5}\times\dfrac{5}{6}+\dfrac{1}{5}\times x\right)\times30=54+26\)
\(\left(\dfrac{4}{6}+\dfrac{1}{5}\times x\right)\times30=80\)
\(\dfrac{4}{6}+\dfrac{1}{5}\times x=\dfrac{8}{3}\)
\(\dfrac{1}{5}\times x=\dfrac{8}{3}-\dfrac{4}{6}\)
\(\dfrac{1}{5}\times x=2\)
\(x=2:\dfrac{1}{5}\)
\(x=2\times5\)
\(x=10\)
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a) x - 1845 = 115 x 2 - 25 x 3
x - 1845 = 230 - 75
x - 1845 = 155
x = 155 + 1845
\(b,230+35x4=x+\frac{700}{5}+30\)
230 + 140 = x + 140 + 30
370 = x + 170
x = 370 - 170
x = 200
a) x - 1845 = 115 x 2 - 25 x 3
x - 1845 = 230 - 75
x - 1845 = 155
x = 155 + 1845
x = 2000
Vậy x = 2000
b) 230 + 35 x 4 = x + 700 / 5+30
370 = x + 140 + 30
370 = x + 170
x = 370 - 170
x = 200
Vậy x = 200
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\(\left(x+1\right)+\left(x+3\right)+\left(x+5\right)=30\\ x+1+x+3+x+5=30\\ 3x+9=30\\ 3x=30-9\\ 3x=21\\ x=21:3\\ x=7\)