tìm x:120 :x -1/4 =3/4
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TT
2
MN
8 tháng 6 2021
\(\dfrac{1}{120}\cdot120+x:\dfrac{1}{3}=-4\)
\(\Leftrightarrow1+x\cdot3=-4\)
\(\Leftrightarrow3x=-5\)
\(\Leftrightarrow x=-\dfrac{5}{3}\)
10 tháng 6 2021
\(\dfrac{1}{120}.120+x:\dfrac{1}{3}=-4\)
\(1+x:\dfrac{1}{3}=-4\)
\(x:\dfrac{1}{3}=-4-1\)
\(x:\dfrac{1}{3}=-5\)
\(x=-5.\dfrac{1}{3}\)
\(x=\dfrac{-5}{3}\)
AC
2
28 tháng 6 2018
a/ \(\frac{x}{2}+\frac{x}{3}+\frac{x}{4}=180\)
\(\Leftrightarrow x\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}\right)=180\)
\(\Leftrightarrow\frac{13}{12}x=180\)
\(\Leftrightarrow x=\frac{2160}{13}\)
b/ \(\frac{1}{x.2}+\frac{2}{x.3}+\frac{3}{x.4}=120\)
\(\Leftrightarrow\frac{1}{x}\left(\frac{1}{2}+\frac{2}{3}+\frac{3}{4}\right)=120\)
\(\Leftrightarrow\frac{1}{x}.\frac{23}{12}=120\)
\(\Leftrightarrow\frac{1}{x}=\frac{1440}{23}\)
\(\Leftrightarrow x=\frac{23}{1440}\)
ND
5
31 tháng 10 2018
Ta có:
10 - 4x + 120:23 = 1 + 42
=> 10 - 4x + 15 = 1 + 16
=> 4x - 5 = 17
=> 4x = 17 + 5 = 22
=> x = 22/4
Vậy: x = 22/4
AH
Akai Haruma
Giáo viên
8 tháng 6 2021
Lời giải:
\(\frac{1}{24.25}+\frac{1}{25.26}+...+\frac{1}{29.30}=\frac{25-24}{24.25}+\frac{26-25}{25.26}+...+\frac{30-29}{29.30}\)
\(=\frac{1}{24}-\frac{1}{25}+\frac{1}{25}-\frac{1}{26}+...+\frac{1}{29}-\frac{1}{30}\)
\(=\frac{1}{24}-\frac{1}{30}=\frac{1}{120}\)
Vậy:
\(\frac{1}{120}.120+x:\frac{1}{3}=-4\)
\(1+x:\frac{1}{3}=-4\)
\(x:\frac{1}{3}=-5\)
\(x=-15\)
10 tháng 6 2021
\(\left(\dfrac{1}{24.25}+\dfrac{1}{25.26}+...+\dfrac{1}{29.30}\right).120+x:\dfrac{1}{3}=-4\)
\(\left(\dfrac{1}{24}-\dfrac{1}{25}+\dfrac{1}{25}-\dfrac{1}{26}+...+\dfrac{1}{29}-\dfrac{1}{30}\right).120+x:\dfrac{1}{3}=-4\)
\(\left(\dfrac{1}{24}-\dfrac{1}{30}\right).120+x:\dfrac{1}{3}=-4\)
\(\dfrac{1}{120}.120+x:\dfrac{1}{3}=-4\)
\(1+x:\dfrac{1}{3}=-4\)
\(x:\dfrac{1}{3}=-4-1\)
\(x:\dfrac{1}{3}=-5\)
\(x=-5.\dfrac{1}{3}\)
\(x=\dfrac{-5}{3}\)
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 \(x=-\frac{5}{3}\)
DH
3
23 tháng 9 2016
(10 - 4.x) + 120 : 8 = 5 mũ 2
(10-4.x) +120 : 8 = 25
(10-4.x)+120 = 25.8
(10-4.x)=200
4.x=200+10
x=210:4
x=52,5
NM
0
11 tháng 9 2017
a) <=>5x-x=57+7
<=> 4x=64
<=> x=16
b) <=>4x=28+12
<=> x=40/4
<=>10
c) th1 x=0
th2 x-3=0
<=>x=3
d) th1 2x-4=0
<=> x=2
th2 x+1=0
<=> x=-1
câu e mình ko biết làm hihi
S
11 tháng 9 2017
a, 5x - 7 = x + 57
5x - x = 57 + 7
4x = 64
x = 64 : 4
x = 16
b, x + 3x - 12 = 28
4x = 28 + 12
4x = 40
x = 10
c, x(x-3) = 0
\(\Rightarrow\orbr{\begin{cases}x=0\\x-3=0\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=3\end{cases}}}\)
d, (2x-4)(x+1)=0
\(\Rightarrow\orbr{\begin{cases}2x-4=0\\x+1=0\end{cases}\Rightarrow\orbr{\begin{cases}x=2\\x=-1\end{cases}}}\)
e, 1+2+...+x=120
=> \(\frac{x\left(x+1\right)}{2}=120\)
=> x(x+1) = 120.2
=>x(x+1) = 240
=> x(x+1) = 15.16
=> x=16
120 : \(x\) - \(\frac14\) = \(\frac34\)
120 : \(x\) = \(\frac34\) + \(\frac14\)
120 : \(x\) = 1
\(x\) = 120 : 1
\(x\) = 120
120 : x - \(\frac14\) = \(\frac34\)
120 : x = \(\frac34\) + \(\frac14\)
120 : x = 1
⇒ x = 120