(2X+1)^3=125
(2x-1)3=125 (2x-1)5=x5
\(\left(2x-1\right)^3=125\)
\(\Leftrightarrow\left(2x-1\right)^3=5^3\)
\(\Leftrightarrow2x-1=5\Leftrightarrow x=3\)
\(------\)
\(\left(2x-1\right)^5=x^5\)
\(\Leftrightarrow2x-1=x\)
\(\Leftrightarrow x=1\)
Tìm số tự nhiên x, biết
a) ( 2 x - 1 ) 3 = 27
b) ( 2 x + 1 ) 3 = 125
c) ( x + 2 ) 3 = ( 2 x ) 3
d) ( 2 x - 1 ) 7 = x 7
(-1/3+2x)^3=-1/125
Ta có \(\left(-\frac{1}{3}+2x\right)^3=\frac{-1}{125}\)
\(\Rightarrow\left(-\frac{1}{3}+2x\right)^3=-\left(\frac{1}{5}\right)^3\)
\(\Rightarrow2x=-\frac{1}{5}+\frac{1}{3}\)
\(\Rightarrow2x=\frac{2}{15}\)
\(\Rightarrow x=\frac{1}{15}\)
\(\Rightarrow2x=-\frac{1}{5}+\frac{1}{3}\)
Tìm số tự nhiên x, biết:
a) ( 2 x + 1 ) 3 = 27 ;
b) ( 2 x - 1 ) 3 = 125
a) Ta có: ( 2 x + 1 ) 3 = 3 3 nên 2x + 1 = 3. Do đó x = 1.
b) Ta có: ( 2 x - 1 ) 3 = 5 3 nên 2x - 1 = 5. Do đó x = 3.
(2x+1)3=125
\(\left(2x+1\right)^3=125\)
\(\Leftrightarrow2x+1=5\)
hay x=2
Giải:
\(\left(2x+1\right)^3=125\)
\(\Rightarrow\) \(\left(2x+1\right)^3=5^3\)
\(\Rightarrow2x+1=5\)
\(\Rightarrow2x=5-1\)
\(\Rightarrow2x=4\)
\(\Rightarrow4:2\)
Vậy \(x=2\)
(2x-1)^3=125
\(\left(2x-1\right)^3=125\)
\(\Rightarrow2x-1=5\Rightarrow2x=6\Rightarrow x=3\)
(2x - 1)3 = 125
<=> (2x - 1)3 = 53
<=> 2x - 1 = 5
<=> 2x = 6
<=> x = 3
\(\Rightarrow2x-1=5\)
\(\Rightarrow2x=6\)
\(\Rightarrow x=3\)
(2x-1)tất cả mũ 4=16
(2x+1)tất cả mũ 3=125
\(\left(2x-1\right)^4=16=\left(\pm2\right)^4\\ =>\left[{}\begin{matrix}2x-1=2\\2x-1=-2\end{matrix}\right.\\ =>\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=-\dfrac{1}{2}\end{matrix}\right.\)
\(\left(2x+1\right)^3=125=5^3\\ =>2x+1=1\\ =>x=2\)
\(\left(2x-1\right)^4=16\)
\(\left(2x-1\right)^4=2^4\)
\(2x-1=2\)
\(2x=3\)
\(x=\dfrac{3}{2}\)
\(\left(2x+1\right)^3=125\)
\(\left(2x+1\right)^3=5^3\)
\(2x+1=5\)
\(2x=4\)
\(x=2\)
( 2x - 1) mũ 3 = 125
\(\left(2x-1\right)^3=125\\ \Rightarrow2x-1=5\\ \Rightarrow2x=6\\ \Rightarrow x=3\)
(2x−1)3 = 125
⇒ 2x − 1 = 5
⇒ 2x = 6
⇒ x = 3
(2x−1)\(^3\) = 125
(2x - 1)\(^3\) = 5\(^3\)
=> 2x - 1 = 5
2x = 5 + 1
2x = 6
x = 6 : 2
x = 3
Vây x = 3
b) (2x + 1)3= 125
(2x+1)3 = 125
<=> (2x+1)3 = 53
<=> 2x+1 = 5
<=> 2x = 4
<=> x = 2