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a: \(\Leftrightarrow\left(\dfrac{12}{25}\right)^x=\dfrac{9}{25}-\dfrac{81}{625}=\dfrac{144}{625}\)
=>x=2
b: =>3x-1=-4
=>3x=-3
hay x=-1
Bài 1:
Ta có: \(x+\left(-\frac{31}{12}\right)^2=\left(\frac{49}{12}\right)^2-x\)
\(\Leftrightarrow2x=\frac{1440}{144}=10\)
\(\Rightarrow x=5\)
Khi đó: \(y^2=\left(\frac{49}{12}\right)^2-5=\frac{1681}{144}\)
=> \(\hept{\begin{cases}y=\frac{41}{12}\\y=-\frac{41}{12}\end{cases}}\)
Bài 1:
\((1-2x)^2=9=3^2=(-3)^2\)
\(\Rightarrow \left[\begin{matrix} 1-2x=3\\ 1-2x=-3\end{matrix}\right.\Rightarrow \left[\begin{matrix} x=-1\\ x=2\end{matrix}\right.\)
Bài 2:
\((x+5)^3=-64=(-4)^3\)
\(\Rightarrow x+5=-4\Rightarrow x=-9\)
Bài 3:
\((3x-5)^2=16=4^2=(-4)^2\)
\(\Rightarrow \left[\begin{matrix} 3x-5=4\\ 3x-5=-4\end{matrix}\right.\Rightarrow \left[\begin{matrix} x=3\\ x=\frac{1}{3}\end{matrix}\right.\)
Bài 4:
\((x-1)^3=27=3^3\)
\(\Rightarrow x-1=3\Rightarrow x=4\)
Bài 5:
\(x^2+x=0\Leftrightarrow x(x+1)=0\)
\(\Rightarrow \left[\begin{matrix} x=0\\ x+1=0\end{matrix}\right.\Rightarrow \left[\begin{matrix} x=0\\ x=-1\end{matrix}\right.\)
Bài 6:
\(5^{x+2}=625=5^4\)
\(\Rightarrow x+2=4\Rightarrow x=2\)
b, \(\left(5x+1\right)^2=\dfrac{36}{49}\)
\(\left(5x+1\right)^2=\left(\pm\dfrac{6}{7}\right)^2\)
\(\Rightarrow\left[{}\begin{matrix}5x+1=\dfrac{6}{7}\\5x+1=-\dfrac{6}{7}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}5x=-\dfrac{1}{7}\\5x=\dfrac{-13}{7}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-\dfrac{1}{35}\\x=\dfrac{-13}{35}\end{matrix}\right.\)
Vậy .....
Nguyễn Thanh Hằng ;Hồng Phúc Nguyễn ;Mới vô; ... các bn giúp mik vs mik đang cần gấp !
a: \(\Leftrightarrow2x-3=x\)
=>x=3
b: \(\Leftrightarrow2^x\cdot\dfrac{1}{2}+\dfrac{5}{4}\cdot2^x=\dfrac{7}{32}\)
=>2^x=1/8
=>x=-3
c: =>2x+7=-4
=>2x=-11
=>x=-11/2
d: =>(4x-3)^2*(4x-4)(4x-2)=0
hay \(x\in\left\{\dfrac{3}{4};1;\dfrac{1}{2}\right\}\)
Ta có ; \(5^x.\left(5^3\right)^2=625\)
\(\Leftrightarrow5^x.5^6=625\)
\(\Leftrightarrow5^{x+6}=5^4\)
<=> x + 6 = 4
<=> x = -2
a,ta có
\(5^x\left(5^3\right)^2=625\)
\(5^x.5^6=5^4\)
\(5^{x+6}=5^4\)
\(x+6=4\)
\(x=-2\)
b, đề sai hay sao đó x=48,9287366