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TD
2
NP
5
NV
1
LL
2
15 tháng 5 2022
a: \(\Leftrightarrow-4< x< -\dfrac{3}{10}\)
mà x là số nguyên
nên \(x\in\left\{-3;-2;-1\right\}\)
b: \(\Leftrightarrow-\dfrac{125}{27}< x< \dfrac{4}{7}\)
mà x là số nguyên
nên \(x\in\left\{-4;-3;-2;-1;0\right\}\)
LG
2
MC
16 tháng 7 2018
\(1.125+\left(x-5\right)=130\)
\(\Leftrightarrow125+x+5=130\)
\(\Leftrightarrow x=0\)
\(2.127-\left(5-x\right)=120\)
\(\Leftrightarrow127-5+x=120\)
\(\Leftrightarrow122+x=120\)
\(\Leftrightarrow x=-2\)
\(3.25-\left(x-3\right)=12-x\)
\(\Leftrightarrow25-x+3=12-x\)
\(\Leftrightarrow\left(25-x+3\right)-\left(12-x\right)=0\)
\(\Leftrightarrow25-x+3-12+x=0\)
\(\Leftrightarrow-x+x=-16\)
Vì \(x\in Z\) Nên \(x\) không tồn tại.
\(4.\left(-2\right)^3-\left(x-5\right)=-3+x\)
\(\Leftrightarrow-8-x+5-x=-3\)
\(\Leftrightarrow-2x=-3+8-5\)
\(\Leftrightarrow-2x=0\)
\(\Leftrightarrow x=0\)
\(5.\left(-2\right)^2-\left(6-x\right)=13\)
\(\Leftrightarrow4-6+x=13\)
\(\Leftrightarrow-2+x=12\)
\(\Leftrightarrow x=14\)
16 tháng 7 2018
1, 125 + (x-5)=130
125+x-5=130
x-5=130-125
x-5=5
x=5+5=10
2, 127-(5-x)=120
127+5+x=120
5+x=120-127
5+x=-7
x=-7-5
x=-12
3, 25-(x-3)=12-x
25+x+3=12-x
28+x=12-x
x+x=12-28
2x=16
x=-8
4, \(\left(-2\right)^3-\left(x-5\right)=-3+x\)
\(\left(-2\right)^3\)+x+5=-3+x
\(\left(-2\right)^3\)+5+(-3)=x+x
-8+5-3=2x
-6=2x
x=-3
5, 3.\(\left(-2\right)^2\)-(6-x)=13
3.(-4)+6+x=13
-12+6+x=13
-6+x=13
x=13+6
x=19
PH
2
27 tháng 4 2020
\(\left(3x-25\right)-\left(x-9\right)=2-x\Leftrightarrow3x-25-x+9=2-x\Leftrightarrow2x-16-2+x=0\Leftrightarrow3x-18=0\)
\(\Leftrightarrow3x=18\Leftrightarrow x=6\)
\(2x+\left(-73-120\right)-\left(20-120\right)=5\Leftrightarrow2x-73-120-20+120=5\Leftrightarrow2x-93=5\)
\(\Leftrightarrow2x=98\Leftrightarrow x=49\)
27 tháng 4 2020
๛๖ۣۜTɦủү❄๖ۣۜAɾĭαηηεツ Trình bày bài cho dễ nhìn nha -.-
\(\left(3x-25\right)-\left(x-9\right)=2-x\)
\(3x-25-x+9=2-x\)
\(\left(3x-x\right)-25+9=2-x\)
\(2x-16=2-x\)
\(2x+x=2+16\)
\(3x=18\)
\(x=6\)
\(2x+\left(-73-120\right)-\left(20-120\right)=5\)
\(2x+\left(-73\right)-120-20+120=5\)
\(2x+\left[\left(-73\right)-20\right]+\left(120-120\right)=5\)
\(2x+\left(-93\right)+0=5\)
\(2x+\left(-93\right)=5\)
\(2x=98\)
\(x=49\)
30 tháng 7 2018
\(a) \frac{4}{5}.x=\frac{8}{35}\)
\(\implies x= \frac{8}{35}:\frac{4}{5}\)
\(\implies x=\frac{8}{35}.\frac{5}{4}\)
\(\implies x=\frac{2}{7}\). Vậy \(x=\frac{2}{7}\)
\(b) \frac{3}{5}x-\frac{1}{2}=\frac{1}{7}\)
\(\implies \frac{3}{5}x=\frac{1}{7}+\frac{1}{2}\)
\(\implies \frac{3}{5}x=\frac{9}{14}\)
\(\implies x=\frac{9}{14}:\frac{3}{5}\)
\(\implies x=\frac{9}{14}.\frac{5}{3} \)
\(\implies x=\frac{15}{14}\). Vậy \(x=\frac{15}{14}\)
\(c) x-25\% x=0,5\)
\(\implies 75\% x=0,5\)
\(\implies \frac{3}{4}x=\frac{1}{2}\)
\(\implies x=\frac{1}{2}:\frac{3}{4}\)
\(\implies x=\frac{1}{2}.\frac{4}{3}\)
\(\implies x=\frac{2}{3}\). Vậy \(x=\frac{2}{3}\)
\(d) (\frac{1}{24.25}+\frac{1}{25.26}+...+\frac{1}{29.30}).120+x:\frac{1}{3}=-4\)
Có: \(\frac{1}{24.25}+\frac{1}{25.26}+...+\frac{1}{29.30}\)
\(=\frac{1}{24}-\frac{1}{25}+\frac{1}{25}-\frac{1}{26}+...+\frac{1}{29}-\frac{1}{30}\)
\(=\frac{1}{24}-\frac{1}{30}\)
\(=\frac{1}{120}\)
Thay vào ta có: \(\frac{1}{120}.120+x:\frac{1}{3}=-4\)
\(\implies 1+x:\frac{1}{3}=-4\)
\(\implies x:\frac{1}{3}=-5\)
\(\implies x=-5.\frac{1}{3}\)
\(\implies x=\frac{-5}{3}\). Vậy \(x=\frac{-5}{3}\)
~ Hok tốt a~
30 tháng 7 2018
\(\frac{4}{5}.x=\frac{8}{35}\) \(\frac{3}{5}x-\frac{1}{2}=\frac{1}{7}\)
\(x=\frac{8}{35}:\frac{4}{5}\) \(\frac{3}{5}x=\frac{1}{7}+\frac{1}{2}\)
\(x=\frac{8}{35}.\frac{5}{4}\) \(\frac{3}{5}x=\frac{9}{14}\)
\(x=\frac{2}{7}\) \(x=\frac{9}{14}:\frac{3}{5}\)
Vậy \(x=\frac{2}{7}\) \(x=\frac{9}{14}.\frac{5}{3}\)
\(x-25\%x=0.5\) \(x=\frac{15}{14}\)
\(x-\frac{1}{4}x=\frac{1}{2}\) Vậy \(x=\frac{15}{14}\)
\(x\left(1-\frac{1}{4}\right)=\frac{1}{2}\) \(\left(\frac{1}{24.25}+\frac{1}{25.26}+...+\frac{1}{29.30}\right).120+x:\frac{1}{3}=-4\)
\(x=\frac{1}{2}:\frac{3}{4}\) \(\left(\frac{1}{24}-\frac{1}{25}+\frac{1}{25}-\frac{1}{26}+...+\frac{1}{29}-\frac{1}{30}\right).120+x:\frac{1}{3}=-4\) \(x=\frac{2}{3}\) \(\left(\frac{1}{24}-\frac{1}{30}\right).120+x:\frac{1}{3}=-4\)
Vậy \(x=\frac{2}{3}\) \(\frac{1}{120}.120+x:\frac{1}{3}=-4\)
\(1+x:\frac{1}{3}=-4\)
\(x:\frac{1}{3}=\left(-4\right)-1\)
\(x:\frac{1}{3}=-5\)
\(x=\left(-5\right).\frac{1}{3}\)
\(x=-\frac{5}{3}\)
Vậy \(x=-\frac{5}{3}\)
5.(x +3) - 25 = 120
5.(x+3) = 120 + 25
5.(x+3) = 145
x + 3 = 145 : 5
x + 3 = 29
x = 29 - 3
x = 26
x=26 nhé