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\(3(x-9)+15=12+243:3^2\)
=> 3x - 27 + 15 = 12 + 243 : 9
=> 3x - 27 + 15 = 12 + 27
=> 3x - 27 + 15 = 39
=> 3x - 27 = 39 - 15
=> 3x - 27 = 24
=> 3x = 24 + 27
=> 3x = 51
=> x = 51 : 3 = 17
Vậy x = 17
\(1170:(x-13)=339-3\cdot10^2\)
=> 1170 : [x-13] = 339 - 3 . 100
=> 1170 : [x - 13] = 339 - 300
=> 1170 : [x-13] = 39
=> x - 13 = 30
=> x = 43
a) 3 ( x - 9 ) + 15 = 12 + 243 : 32
3 ( x - 9 ) + 15 = 12 + 27
3 ( x - 9 ) + 15 = 39
3 ( x - 9 ) = 39 - 15
3 ( x - 9 ) = 24
x - 9 = 24 : 3
x - 9 = 8
x = 8 + 9
x = 17
Vậy x = 17
b) 1170 : ( x - 13 ) = 339 - 3 . 102
1170 : ( x - 13 ) = 339 - 300
1170 : ( x - 13 ) = 39
x - 13 = 1170 : 39
x - 13 = 30
x = 30 + 13
x = 43
Vậy x = 43
=))
a: =>1170:(x-13)=39
=>x-13=1170/39=30
=>x=43
b: \(\Leftrightarrow x^{1000}\cdot x^{999}-x=0\)
=>\(x\left(x^{1998}-1\right)=0\)
=>\(\left[{}\begin{matrix}x=0\\x^{1998}-1=0\end{matrix}\right.\Leftrightarrow x\in\left\{0;1;-1\right\}\)
a)
\(\begin{array}{l}\left( {9x - {2^3}} \right):5 = 2\\9x - {2^3} = 2.5\\9x - 8 = 10\\9x = 18\\x = 2\end{array}\)
Vậy \(x = 2\)
b)
\(\begin{array}{l}\left[ {{3^4} - \left( {{8^2} + 14} \right):13} \right]x = {5^3} + {10^2}\\\left[ {81 - \left( {64 + 14} \right):13} \right]x = 125 + 100\\\left[ {81 - 78:13} \right]x = 125 + 100\\\left[ {81 - 6} \right]x = 225\\75x = 225\\x = 3\end{array}\)
Vậy \(x = 3\)
1170-(x-13) = 339 - 3x100
1170 - (x-13) = 339 - 300
1170-(x-13) = 39
x-13 = 1170-39
x-13 = 1131
x = 1131+13 =11 44
1170 : (x - 13) = 339 - 3 . 102
1170 : (x -13) = 339 - 3 . 100
1170 : (x -13) = 339 - 300
1170 : (x - 13) = 39
x - 13 = 1170 : 39
x - 13 = 30
x = 30 + 13
x = 43
vậy x = 43
ủng hô mk nha
1: =>3^x=81
=>x=4
2: =>2^x=8
=>x=3
3: =>x^3=2^3
=>x=2
4: =>x^20-x=0
=>x(x^19-1)=0
=>x=0 hoặc x=1
5: =>2^x=32
=>x=5
6: =>(2x+1)^3=9^3
=>2x+1=9
=>2x=8
=>x=4
7: =>x^3=115
=>\(x=\sqrt[3]{115}\)
8: =>(2x-15)^5-(2x-15)^3=0
=>(2x-15)^3*[(2x-15)^2-1]=0
=>2x-15=0 hoặc (2x-15)^2-1=0
=>2x-15=0 hoặc 2x-15=1 hoặc 2x-15=-1
=>x=15/2 hoặc x=8 hoặc x=7
1. Tìm số tự nhiên x biết:
1) \(3^x.3=243\)
\(3^x=243:3\)
\(3^x=81\)
\(3^x=3^4\)
\(\Rightarrow x=4\)
_____
2) \(7.2^x=56\)
\(2^x=56:7\)
\(2^x=8\)
\(2^x=2^3\)
\(\Rightarrow x=3\)
_____
3) \(x^3=8\)
\(x^3=2^3\)
\(\Rightarrow x=3\)
_____
4) \(x^{20}=x\)
\(x^{20}-x=0\)
\(x\left(x^{19}-1\right)=0\)
\(\Rightarrow x=0\) hoặc \(x=1\)
5) \(2^x-15=17\)
\(2^x=17+15\)
\(2^x=32\)
\(2^x=2^5\)
\(\Rightarrow x=5\)
_____
6) \(\left(2x+1\right)^3=9.81\)
\(\left(2x+1\right)^3=729=9^3\)
\(\rightarrow2x+1=9\)
\(2x=9-1\)
\(2x=8\)
\(x=8:2\)
\(\Rightarrow x=4\)
_____
7) \(x^6:x^3=125\)
\(x^3=125\)
\(x^3=5^3\)
\(\Rightarrow x=5\)
_____
8) \(\left(2x-15\right)^5=\left(2x-15\right)^3\)
\(\rightarrow\left(2x-15\right)^5-\left(2x-15\right)^3=0\)
\(\left(2x-15\right)^3.\left[\left(2x-15\right)^2-1\right]=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left(2x-15\right)^3=0\\\left(2x-15\right)^2-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{15}{2}\\x=7\\x=8\end{matrix}\right.\)
_____
9) \(3^{x+2}-5.3^x=36\)
\(3^x.\left(3^2-5\right)=36\)
\(3^x.\left(9-5\right)=36\)
\(3^x.4=36\)
\(3^x=36:4\)
\(3^x=9\)
\(3^x=3^2\)
\(\Rightarrow x=2\)
_____
10) \(7.4^{x-1}+4^{x+1}=23\)
\(\rightarrow7.4^{x-1}+4^{x-1}.4^2=23\)
\(4^{x-1}.\left(7+4^2\right)=23\)
\(4^{x-1}.\left(7+16\right)=23\)
\(4^{x-1}.23=23\)
\(4^{x-1}=23:23\)
\(4^{x-1}=1\)
\(4^{x-1}=4^1\)
\(\rightarrow x-1=0\)
\(x=0+1\)
\(\Rightarrow x=1\)
Chúc bạn học tốt
a, 1170 : x - 13 = 339 . 3 . 10 2
1170:(x - 13) = 339 - 3.100
1170:(x - 13) = 39
x - 13 = 1170:39 = 30
x = 30+13 = 43
b, 3 x - 9 + 15 = 12 + 243 : 3 2
3(x - 9) + 15 = 12+243:9
3(x - 9)+15 = 12+27
3(x - 9)+15 = 39
3(x - 9) = 24
x - 9 = 8
x = 17