[ 30%x + 2+1/2] + 3/5 = 2+1/2 giúp mik với
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1, \(\left(y+7\right)\left(y-5\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}y+7=0\\y-5=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}y=-7\\y=5\end{matrix}\right.\)
2, \(25-\left(30+x\right)=\left(-24+3\right)\)
\(\Rightarrow25-\left(30+x\right)=-21\)
\(\Rightarrow30+x=25-\left(-21\right)\)
\(\Rightarrow30+x=25+21\)
\(\Rightarrow30+x=46\)
\(\Rightarrow x=46-30\)
\(\Rightarrow x=16\)
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bạn đã kiểm tra kĩ chưa vậy?mình đọc đề câu B mà loạn não luôn á;-;
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1.
a) \(2^x=128\)
\(2^x=2^7\)
\(=>x=7\)
b) \(8^{x-1}=64\)
\(8^{x-1}=8^2\)
\(=>x-1=2\)
\(x=2+1\)
\(=>x=3\)
c) \(3+3^x=30\)
\(3^x=30-3\)
\(3^x=27=3^3\)
\(=>x=3\)
d) \(\left(x+2\right)=64\) -> đề có thiếu không vậy?
e) \(3^2.x=3^5\)
\(x=3^5:3^2\)
\(=>x=3^3=27\)
f) \(\left(2x-1\right)^3=343\)
\(\left(2x-1\right)^3=7^3\)
\(=>2x-1=7\)
\(2x=7+1\)
\(2x=8\)
\(x=8:2\)
\(=>x=4\)
\(#Wendy.Dang\)
a,\(2^x\)=128 b,\(8^{x-1}\)=64 c,3+\(3^x\)=30 d,x+2=64
\(2^7\)=128 \(8^{x-1}\)=\(8^2\) \(3^x\)=30-3 x=64-2
=>x=7 =>x-1=2 \(3^x\)=27 x=62
x=2+1=3 \(3^x\)=\(3^3\)
=>x=3
e,\(3^2\).x=\(3^5\) f,(2x-\(1^3\))=343
x=\(3^5\):\(3^2\) 2x=1+343
x=27 2x=344
x=344:2
x=172
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\(\frac{2}{5}\times\frac{1}{2}-\frac{2}{5}\times\frac{1}{3}-\frac{2}{5}\times\)\(\frac{1}{6}\)
\(=\frac{2}{5}\times\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\)
\(=\frac{2}{5}\times\frac{0}{6}\)
\(=\frac{2}{5}\times0\)
\(=0\)
\(\frac{2}{5}\times\frac{1}{2}-\frac{2}{5}\times\frac{1}{3}-\frac{2}{5}\times\frac{1}{6}\)
\(=\frac{2}{5}\times\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\)
\(=\frac{2}{5}\times0\)
\(=0\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) -12x + 60 + 21 - 7x =15
-12x - 7x + 81 = 15
-19x = 15 - 81
-19x = -66
x= -66 : (-19)
x = \(\frac{66}{19}\)
Vậy x = \(\frac{66}{19}\)
b) 30x + 60 - 6x + 30 - 24x= 100
30x - 6x - 24x + 60 +30= 100
x ( 30 - 6- 24 ) + 90 = 100
x. 0 + 90 =100
x. 0 =10 ( vô lý )
\(\Rightarrow\) x \(\in\phi\)
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\(\left(1+\dfrac{2}{3}\right).\left(1+\dfrac{2}{4}\right).\left(1+\dfrac{2}{5}\right)....\left(1+\dfrac{2}{2020}\right).\left(1+\dfrac{2}{2021}\right)\)
= \(\dfrac{5}{3}.\dfrac{6}{4}.\dfrac{7}{5}.\dfrac{8}{6}.\dfrac{9}{7}....\dfrac{2022}{2020}.\dfrac{2023}{2021}\)
= \(\dfrac{1}{3}.\dfrac{1}{4}.2022.2023\)
= \(\dfrac{337.2023}{2}\)
= \(\dfrac{\text{681751}}{2}\)
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a: x/3-1/6=1/5
=>x/3=11/30
hay x=11/90
b: =>1/2x=2
hay x=4
c: =>2/3:x=-7-1/3=-22/3
=>x=-1/11
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 10 - x : 2 = 1
x: 2 = 9
x = 18
b) x:4 + 3 x 2 = 7
x:4 + 6 = 7
x:4 = 1
x = 4
c) 2: x + 5 = 6
2: x = 1
x = 2
+4.10-x:2=1
40-x:2=1
x:2=40-1
x:2=39
x:2=19,5
+5.x:4+3*2=7
5.x:4+6=7
5.x:4=7-6=1
5.x=1.4=4
x=4:5
x=0,8
+6.2:x+5=6
12:x=6-5
12:x=1
x=12:1
x=12
+7.2*x*3*5=30
14.x.15=30
14.x=2
x=2:14
x=1/7
+8.2*x:10*2=1
16.x:20=1
16.x=20
x=20:16
x=1,25
9.18:x-5*2=8
10.5*5-2:x=24
\(\frac{3x}{10}+\frac{5}{2}+\frac{3}{5}=\frac{5}{2}\)
=> \(\frac{3}{10}x=-\frac{3}{5}\)
=>x=-2
\(\left[30\%x+2+\frac{1}{2}\right]+\frac{3}{5}=2+\frac{1}{2}\)
\(\left[30\%x+\frac{5}{2}\right]+\frac{3}{5}=\frac{5}{2}\)
\(30\%+\frac{5}{2}=\frac{5}{2}-\frac{3}{5}\)
\(30\%x+\frac{5}{2}=\frac{19}{10}\)
\(\frac{3}{10}x=\frac{19}{10}-\frac{5}{2}\)
\(\frac{3}{10}x=\frac{-3}{5}\)
\(x=\frac{-3}{5}:\frac{3}{10}\)
\(x=-2\)
Vậy x=-2