tìm x
75. (3x-23) = 74.72
Giải:Ta có:75.(3x-23)=74.72
\(\Rightarrow7^5.\left(3x-2^3\right)=7^6\)
\(\Rightarrow3x-2^3=\frac{7^6}{7^5}\Rightarrow3x-2^3=7\)
\(\Rightarrow3x=7+2^3\Rightarrow3x=15\Rightarrow x=5\)
Vậy....................
75. (3x-23) = 74.72
75 . ( 3x - 23 ) = 76
3x - 23 = 7
3x - 8 = 7
3x = 7 + 8
3x = 15
x = 15 : 3
x = 5
Ta có : \(7^5.\left(3x-2^3\right)=7^4.7^2\)
\(\Rightarrow3x-2^3=7\)
\(\Rightarrow3x=7+8=15\)
\(\Rightarrow x=15:3=5\)
75 . (3x - 23) = 74 . 72
75 . (3x - 23) = 76
(3x - 23) = 76 : 75
3x - 8 = 7
3x = 7 + 8
3x = 15
x = 5
\(7^5.\left(3x-2^3\right)=7^4.7^2\)
\(7^5.\left(3x-2^3\right)=7^6\)
\(3x-8\) \(=7^6\div7^5\)
\(3x-8\) \(=7\)
\(3x\) \(=7+8\)
\(3x\) \(=15\)
\(x\) \(=15\div3\)
\(\Rightarrow\) \(x\) \(=5\)
