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a) 3x – 15 = 25 – 5x
=> 3x + 5x = 25 + 15
=> 8x = 40
=> x = 5
b) 3x - 17 = 2x – 7
=> 3x - 2x = -7 + 17
=> x = 10
c) 2x – 17 = – (3x – 18)
=> 2x - 17 = -3x + 18
=> 2x + 3x = 18 + 17
=> 5x = 35
=> x = 7
d) 3x – 14 = 2(x – 9) + 1
=> 3x - 14 = 2x - 18 + 1
=> 3x - 2x = -18 + 1 + 14
=> x = -3
f) (x – 5)2 = 9
\(\Rightarrow\left[{}\begin{matrix}x-5=3\\x-5=-3\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=8\\x=2\end{matrix}\right.\)
a) Ta có: \(3x-15=25-5x\)
\(\Leftrightarrow3x-15-25+5x=0\)
\(\Leftrightarrow8x-40=0\)
\(\Leftrightarrow8x=40\)
hay x=5
Vậy: x=5
b) Ta có: \(3x-17=2x-7\)
\(\Leftrightarrow3x-17-2x+7=0\)
\(\Leftrightarrow x-10=0\)
hay x=10
Vậy: x=10
c) Ta có: \(2x-17=-\left(3x-18\right)\)
\(\Leftrightarrow2x-17=-3x+18\)
\(\Leftrightarrow2x-17+3x-18=0\)
\(\Leftrightarrow5x-35=0\)
\(\Leftrightarrow5x=35\)
hay x=7
Vậy: x=7
d) Ta có: \(3x-14=2\left(x-9\right)+1\)
\(\Leftrightarrow3x-14=2x-18+1\)
\(\Leftrightarrow3x-14-2x+18-1=0\)
\(\Leftrightarrow x+3=0\)
\(\Leftrightarrow x=-3\)
Vậy: x=-3
f) Ta có: \(\left(x-5\right)^2=9\)
\(\Leftrightarrow\left[{}\begin{matrix}x-5=3\\x-5=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=8\\x=2\end{matrix}\right.\)
Vậy: \(x\in\left\{2;8\right\}\)
a) x10 = 1x
=> x10 = 1
=> x10 = 110 => x = 1
b) x10 = x
=> x10 - x = 0
=> x(x9 - 1) = 0
=> \(\orbr{\begin{cases}x=0\\x^9-1=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=0\\x=1\end{cases}}\)
c) x5 = 32 => x5 = 25 => x = 2
d) 3x = 81 => 3x = 34 => x = 4
e) 25x = 1252
=> 25x = (53)2
=> (52)x = 56
=> 52x = 56
=> 2x = 6 => x = 3
f) (2x - 15)5 = (2x - 15)3
=> (2x - 15)5 - (2x - 15)3 = 0
=> (2x - 15)3 [(2x - 15)2 - 1] = 0
=> \(\orbr{\begin{cases}\left(2x-15\right)^3=0\\\left(2x-15\right)^2-1=0\end{cases}}\)
=> \(\orbr{\begin{cases}2x-15=0\\\left(2x-15\right)^2=1\end{cases}\Rightarrow}\orbr{\begin{cases}x=\frac{15}{2}\\\left(2x-15\right)^2=\left(\pm1\right)^2\end{cases}}\)
+) 2x - 15 = 1 => 2x = 16 => x = 8
+) 2x - 15 = -1 => 2x = 14 => x = 7
Vậy x = 8,x = 7
`\color{grey}\text{#071931}`
`(4 + 2x) * (9 - 3x) = 0`
TH1: `4 + 2x = 0 => 2x = -4 => x = -2`
TH2: `9 - 3x = 0 => 3x = 9 => x = 3`
Vậy, `x \in {-2; 3}`
____
`(3x - 19)^3 = 125`
`=> (3x - 19)^3 = 5^3`
`=> 3x - 19 = 5`
`=> 3x = 24`
`=> x = 8`
Vậy, `x = 8.`
Ta có : (2x + 1)3 = 125
=> (2x + 1)3 = 53
=> 2x + 1 = 5
=> 2x = 4
=> x = 2
Ta có : (4x - 1)2 = 25 x 9
=> (4x - 1)2 = 52.32
=> (4x - 1)2 = 152
\(\Leftrightarrow\orbr{\begin{cases}4x-1=15\\4x-1=-15\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}4x=16\\4x=-14\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=4\\x=-\frac{7}{2}\end{cases}}\)
bài 1
a) 155 - 10.(x+1) = 55
=>10 .(x+1) = 100
=>x + 1 = 10
=>x = 9
còn lại tương tự
a)\(\left(2x+1\right)^3=5^3\)
\(\Rightarrow2x+1=5\)
\(2x=5-1\)
\(2x=4\)
\(x=4:2\)
\(x=2\)
\(b,\left(2x-1\right)^3=125\)
\(\Rightarrow2x-1=5\)
\(2x=5+1\)
\(2x=6\)
\(x=6:2=3\)
b) \(\left(2x-1\right)^3=125\)
\(\left(2x-1\right)^3=5^3\)
\(2x-1=5\)
\(2x=5+1\)
\(2x=6\)
\(x=6:2\)
\(x=3\)
a ) 126 - 2x = 12 - ( -28 )
126 - 2x = 40
2x = 126 - 40
2x = 86
x = 86 : 2
x = 43
b ) 25 - 5( x + 1 ) = 30 - 125
25 - ( 5x + 5 ) = -95
25 - 5x - 5 = -95
20 - 5x = -95
5x = 20 - ( - 95 )
5x = 115
x = 115 : 5
x = 23
c ) I 3x - 1 I - 25 = 73
I 3x - 1 I = 73 + 25
I 3x - 1 I = 98
=> 3x - 1 = 98 hoặc 3x - 1 = -98
=> 3x = 98 + 1 hoặc 3x = -98 + 1
=> 3x = 99 hoặc 3x = -97
=> x = 99 : 3 hoặc x = -97 : 3
=> x = 33 hoặc x = -93/3
d ) 2( x + 2 ) - 6 = 120 - 4x
2x + 4 - 6 = 120 - 4x
2x - 2 = 120 - 4x
2x + 4x = 120 + 2
6x = 122
x = 122 : 6
x = 61/3
<=> -3x = 2x + 15 - 25
<=> -3x - 2x = 15-25
<=> -5x = - 10
<=> 5x = 10
<=> x = 10 : 2
<=> x = 5
Vậy x = 5
-125 + 3x = 25 + (-15) - 2x
3x + 2x = 25 + (-15) + (-125)
5x = 10 + (-125)
5x = -115
x = -115 : 5
x = -23
Vậy x = -23
Nguyễn Hoàng Nam chuyển -125 từ vế trái sang vế phải sai rồi đấy.