So sánh :
\(\left(-\frac{1}{27}\right)^{53}và\left(-\frac{1}{243}\right)^{23}\)
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\(\left(-\frac{1}{27}\right)^{53}=\left[\left(-\frac{1}{3}\right)^3\right]^{53}=\left(-\frac{1}{3}\right)^{159}\)
\(\left(-\frac{1}{243}\right)^{23}=\left[\left(-\frac{1}{3}\right)^5\right]^{23}=\left(-\frac{1}{3}\right)^{115}\)
Vì\(\left(-\frac{1}{3}\right)^{159}< \left(-\frac{1}{3}\right)^{115}\)nên: \(\left(-\frac{1}{27}\right)^{53}< \left(-\frac{1}{243}\right)^{23}\)
Nhung ơi tớ câu c tớ làm giống cái cậu Triều nhưng ko có dấu trừ
a)Ta có:
\(\left(\frac{1}{2}\right)^{27}=\left[\left(\frac{1}{2}\right)^3\right]^9=\left(\frac{1}{8}\right)^9\)
\(\left(\frac{1}{3}\right)^{18}=\left[\left(\frac{1}{3}\right)^2\right]^9=\left(\frac{1}{9}\right)^9\)
Vì \(\left(\frac{1}{8}\right)^9>\left(\frac{1}{9}\right)^9\) nên \(\left(\frac{1}{2}\right)^{27}>\left(\frac{1}{3}\right)^{18}\)
\(\left(\frac{1}{27}\right)^{23}=\frac{1^{23}}{27^{23}}=\frac{1}{\left(3^3\right)^{23}}=\frac{1}{3^{69}}\)
\(\left(\frac{1}{81}\right)^{16}=\frac{1^{16}}{81^{16}}=\frac{1}{\left(3^4\right)^{16}}=\frac{1}{3^{64}}\)
Vì 369 > 364
\(\frac{1}{3^{69}}< \frac{1}{3^{64}}\)
\(\left(\frac{1}{27}\right)^{23}=\frac{1^{23}}{27^{23}}=\frac{1}{\left(3^3\right)^{23}}=\frac{1}{3^{69}}\)
\(\left(\frac{1}{81}\right)^{16}=\frac{1^{16}}{81^{16}}=\frac{1}{\left(3^4\right)^{16}}=\frac{1}{3^{64}}\)
Vì 369 > 364
=> \(\frac{1}{3^{69}}< \frac{1}{3^{64}}\)
=> \(\left(\frac{1}{27}\right)^{23}< \left(\frac{1}{81}\right)^{16}\)
\(-\frac{1}{27}=-\frac{1}{3^3}\) => \(\left(-\frac{1}{27}\right)^{53}=\left(\left(-\frac{1}{3}\right)^3\right)^{53}=\left(-\frac{1}{3}\right)^{159}\)
\(-\frac{1}{243}=-\frac{1}{3^5}\) => \(\left(-\frac{1}{243}\right)^{23}=\left(\left(-\frac{1}{3}\right)^5\right)^{23}=\left(-\frac{1}{3}\right)^{115}\)
vẬY \(\left(-\frac{1}{27}\right)^{53}< \left(-\frac{1}{243}\right)^{23}\)
\(\left(\frac{-1}{27}\right)^{53}\)=\(\left(\frac{-1}{3}\right)^{3X53}\)=\(\left(\frac{-1}{3}\right)^{159}\)
\(\left(\frac{-1}{243}\right)^{23}\)=\(\left(\frac{-1}{3}\right)^{5X23}\)=\(\left(\frac{-1}{3}\right)^{115}\)
=>\(\left(\frac{-1}{3}\right)^{159}\)>\(\left(\frac{-1}{3}\right)^{115}\)
=>\(\left(\frac{-1}{27}\right)^{53}\)>\(\left(\frac{-1}{243}\right)^{23}\)