\(11,\left(-7\right)^x=\dfrac{1}{49}\)
\(\left(-7\right)^x=\dfrac{1}{7^2}\)
\(\left(-7\right)^x=\left(-7\right)^{-2}\)
\(x=-2\)
Vậy \(x=-2\)
\(12,\left(-10\right)^x=-\dfrac{1}{10}\)
\(\left(-10\right)^x=\left(-10\right)^{-1}\)
\(x=-1\)
Vậy \(x=-1\)
\(13,\left(-10\right)^x=\dfrac{1}{100}\)
\(\left(-10\right)^x=\dfrac{1}{10^2}\)
\(\left(-10\right)^x=\left(-10\right)^{-2}\)
\(x=-2\)
Vậy \(x=-2\)
\(14,\left(-100\right)^x=\dfrac{1}{10000}\)
\(\left(-100\right)^x=\dfrac{1}{100^2}\)
\(\left(-100\right)^x=\left(-100\right)^{-2}\)
\(x=-2\)
Vậy \(x=-2\)
\(15,\left(\dfrac{1}{2}\right)^x=\dfrac{1}{32}\)
\(\left(\dfrac{1}{2}\right)^x=\dfrac{1}{2^5}\)
\(\left(\dfrac{1}{2}\right)^x=\left(\dfrac{1}{2}\right)^5\)
\(x=5\)
Vậy \(x=5\)
\(16,\dfrac{343}{125}=\left(\dfrac{7}{5}\right)^x\)
\(\left(\dfrac{7}{5}\right)^3=\left(\dfrac{7}{5}\right)^x\)
\(3=x\)
Vậy \(x=3\)
