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Bài 1: \(\left(\frac{-1}{16}\right)^{100}=\frac{1}{\left(2^4\right)^{100}}=\frac{1}{2^{400}}>\frac{1}{2^{500}}=\left(\frac{-1}{2}\right)^{500}.\)
Bài 2: \(100^{99}+1>100^{68}+1\Rightarrow\frac{1}{100^{99}+1}< \frac{1}{100^{68}+1}\Rightarrow\frac{-99}{100^{99}+1}>\frac{-99}{100^{68}+1}\)
\(\Rightarrow100+\frac{-99}{100^{99}+1}>100+\frac{-99}{100^{68}+1}\Rightarrow\frac{100^{100}+1}{100^{99}+1}>\frac{100^{69}+1}{100^{68}+1}\)
Ta có:
\(\left(\dfrac{1}{16}\right)^{100}\)giữ nguyên
\(\left(\dfrac{-1}{2}\right)^{500}=\left[\left(\dfrac{-1}{2}\right)^5\right]^{100}=\left(\dfrac{-1}{32}\right)^{100}\)
Vì \(\left(\dfrac{1}{16}\right)^{100}>\left(\dfrac{-1}{32}\right)^{100}\Rightarrow\left(\dfrac{1}{16}\right)^{100}>\left(\dfrac{-1}{2}\right)^{500}\)
\(\frac{7x-5y}{500}=\frac{9x-5z}{300}=\frac{9y-7z}{100}=\frac{7xz-5yz}{500z}=\frac{9xy-5yz}{300y}=\frac{9xy-7zx}{100x}\)
áp dụng t/c dãy tỉ số bằng nhau ta có:
\(\frac{7x-5y}{500}=\frac{9x-5z}{300}=\frac{9y-7z}{100}=\)
\(\frac{7xz-5yz}{500z}=\frac{9xy-5yz}{300y}=\frac{9xy-7zx}{100x}=\frac{7xz-5yz-9xy+5yz+9xy-7zx}{500z-300y+100x}=0\)
\(\frac{7x-5y}{500}=0\Rightarrow7x=5y\Rightarrow\frac{x}{5}=\frac{y}{7}\)(1)
\(\frac{9x-5z}{300}=0\Rightarrow9x=5z\Rightarrow\frac{z}{9}=\frac{x}{5}\)(2)
\(\frac{9y-7z}{100}=0\Rightarrow9y=7z\Rightarrow\frac{y}{7}=\frac{z}{9}\)(3)
từ (1),(2),(3) => đpcm
a, Có: \(25^{200}=\left(5^2\right)^{200}=5^{400}\)
Vì \(5^{400}=5^{400}\) mà \(25^{200}=5^{400}\Rightarrow5^{400}=25^{200}\)
c, Có:
a/ 263 và 342
Ta có: 263=(23)21=821
342=(32)21=921
mà 821<921
vậy 263<342
b/5400 và 25200
Ta có: 25200=(52)200=5400
mà 5400=5400
vậy 5400=25200
c/ \(\left(\dfrac{-1}{16}\right)^{100}v\text{à}\left(\dfrac{-1}{2}\right)^{500}\)
Ta có: \(\left(\dfrac{-1}{2}\right)^{500}=\left(\left(\dfrac{-1}{2}\right)^5\right)^{100}=\left(\dfrac{-1}{32}\right)^{100}\)
mà: \(\left(\dfrac{-1}{16}\right)^{100}< \left(\dfrac{-1}{32}\right)^{100}\)
vậy\(\left(\dfrac{-1}{16}\right)^{100}< \left(\dfrac{-1}{2}\right)^{500}\)
Bạn tham khảo nhé
a ) Ta có :
\(\left(-\frac{1}{5}\right)^{300}=\left(\frac{1}{5}\right)^{300}=\frac{1}{5^{300}}=\frac{1}{\left(5^3\right)^{100}}=\frac{1}{125^{100}}\)
\(\left(-\frac{1}{3}\right)^{500}=\left(\frac{1}{3}\right)^{500}=\frac{1}{3^{500}}=\frac{1}{\left(3^5\right)^{100}}=\frac{1}{243^{100}}\)
Do \(\frac{1}{125^{100}}>\frac{1}{243^{100}}\left(125^{100}< 243^{100}\right)\)
\(\Rightarrow\left(-\frac{1}{5}\right)^{300}>\left(-\frac{1}{3}\right)^{500}\)
b )
Ta có :
\(2550^{10}=\left(50.51\right)^{10}=50^{10}.51^{10}\)
\(50^{20}=50^{10}.50^{10}\)
Do \(50^{10}.51^{10}>50^{10}.50^{10}\)
\(\Rightarrow50^{20}< 2550^{10}\)
c )
Ta có :
\(2^{100}=\left(2^4\right)^{25}=16^{25}\)
\(3^{75}=\left(3^3\right)^{25}=27^{25}\)
\(5^{50}=\left(5^2\right)^{25}=25^{25}\)
Do \(16^{25}< 25^{25}< 27^{25}\)
\(\Rightarrow2^{100}< 5^{50}< 3^{75}\)
400 :))
-400
-400
-400 nha bạn
-400.
-400