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\(30-\left[4\left(x-2\right)+15\right]=3\) \(\left(8x-120:4\right).3^3=3^6\)
\(4\left(x-2\right)+15=27\) \(\left(8x-120:4\right)=27\)
\(4\left(x-2\right)=12\) \(8x-30=27\)
\(x-2=3\) \(8x=57\)
\(x=5\) \(x=\frac{57}{8}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Lời giải:
\(\left\{x^2-[8^2-(5^2-8.3)^3-7.9]^3-4.12\right\}^3=1\\ \Rightarrow x^2-[8^2-(5^2-8.3)^3-7.9]^3-4.12=1\\ \Rightarrow x^2-(64-1-63)^3-48=1\\ \Rightarrow x^2-48=1\\ \Rightarrow x^2=49=7^2=(-7)^2\\ \Rightarrow x=\pm 7\)
![](https://rs.olm.vn/images/avt/0.png?1311)
2a/ 2x - 3 = 16 => 2x - 3 = 24 => x - 3 = 4 => x = 7
b/ {x2 - [82 - (52 - 8.3)3 - 7.9]3 - 4.12}3 = 1
=> x2 - [82 - (52 - 8.3)3 - 7.9]3 - 4.12 = 1
=> x2 - [64 - (25 - 8.3)3 - 7.9]3 = 1 + 4.12 = 49
=> x2 - (64 - 13 - 63)3 = 49
=> x2 - 0 = 49
=> x2 = 49
=> x = 7
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 120 - 5 . ( x + 2 ) = 45
5 . (x + 2) = 120 - 45
5 . (x + 2) = 75
x + 2 = 75 : 5
x + 2 = 15
x = 17
b) ( 2.x - 3 )2 = 49
( 2.x - 3 )2 = 72
( 2.x - 3 ) = 7
2x = 10
x = 5
![](https://rs.olm.vn/images/avt/0.png?1311)
2a/ 2x - 3 = 16 => 2x - 3 = 24 => x - 3 = 4 => x = 7
b/ {x2 - [82 - (52 - 8.3)3 - 7.9]3 - 4.12}3 = 1
=> x2 - [82 - (52 - 8.3)3 - 7.9]3 - 4.12 = 1
=> x2 - [64 - (25 - 24)3 - 63]3 - 48 = 1
=> x2 - (64 - 1 - 63)3 = 1 + 48
=> x2 - 0 = 49
=> x2 = 49
=> x = 7
15: \(\Leftrightarrow\left\{x^2-\left[8^2-\left(25-24\right)^3-63\right]^3-48\right\}=1\)
\(\Leftrightarrow x^2-48=1\)
=>x=7 hoặc x=-7