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a) \(A=\sqrt{140+1}và\sqrt{140}+\sqrt{1}\)
Ta có: \(\sqrt{140+1}=\sqrt{141}\approx11.87\)
\(\sqrt{140}+\sqrt{1}\approx12.83\) 11.8
\(\Rightarrow\) \(11.87>12.83\)
\(\Rightarrow\) \(\sqrt{140+1}>\sqrt{140}+1\)
b) \(A=\sqrt{222+2}\) và \(B=\sqrt{222}+\sqrt{2}\)
Ta có : \(A=\sqrt{222}+2\)
\(=\sqrt{224}\approx15\)
\(B=\sqrt{222}+\sqrt{2}\)
\(B=\sqrt{222}+\sqrt{2}\approx16.31\)
\(\Rightarrow\) \(A< B\)
NOTE: Đây cũng là cách giải của lớp 9 nên e xem thử để hỏi a nha
1)Ta có:\(ac=b^2\Rightarrow\frac{a}{b}=\frac{b}{c},ab=c^2\Rightarrow\frac{c}{a}=\frac{b}{c}\)
\(\Rightarrow\frac{a}{b}=\frac{c}{a}=\frac{b}{c}=\frac{a+c+b}{b+a+c}=1\)(T/C...)
\(\Rightarrow a=b=c\)
\(\Rightarrow M=\frac{b^{333}}{a^{111}\cdot c^{222}}=\frac{b^{333}}{b^{111}\cdot b^{222}}=\frac{b^{333}}{b^{333}}=1\)
\(B=-1+\frac12-\frac{1}{2^2}+\cdots-\frac{1}{2^{2n}}+\frac{1}{2^{2n+1}}\)
=>\(2B=-2+1-\frac12+\cdots-\frac{1}{2^{2n-1}}+\frac{1}{2^{2n}}\)
=>\(2B+B=-2+1-\frac12+\cdots-\frac{1}{2^{2n-1}}+\frac{1}{2^{2n}}-1+\frac12-\frac{1}{2^2}+\cdots-\frac{1}{2^{2n}}+\frac{1}{2^{2n+1}}\)
=>\(3B=-2+\frac{1}{2^{2n+1}}=\frac{-2^{2n+2}+1}{2^{2n+1}}\)
=>\(B=\frac{-2^{2n+2}+1}{3\cdot2^{2n+1}}\)
a: \(\left(-1\right)\left(-1\right)^2\cdot\left(-1\right)^3\cdot\ldots\cdot\left(-1\right)^{2014}\)
\(=\left(-1\right)^{1+2+\cdots+2014}\)
\(=\left(-1\right)^{2014\cdot\frac{2015}{2}}=\left(-1\right)^{1007\cdot2015}=-1\)
b: \(\frac17\left(\frac{555}{222}+\frac{4444}{12221}+\frac{33333}{244442}+\frac{11}{130}+\frac{13}{60}\right)\)
\(=\frac17\left(\frac52+\frac{4}{11}+\frac{3}{22}+\frac{11}{130}+\frac{13}{60}\right)\)
\(=\frac17\left(3+\frac{13}{60}+\frac{11}{130}\right)=\frac17\cdot\frac{515}{156}=\frac{515}{1092}\)
1. Tính
\(\frac{2^7\cdot9^3}{6^5\cdot8^2}=\frac{2^7\cdot\left(3^2\right)^3}{\left(3\cdot2\right)^5\cdot\left(2^3\right)^2}=\frac{2^7\cdot3^6}{3^5\cdot2^5\cdot2^6}=\frac{2^7\cdot3^5\cdot3}{3^5\cdot2^{11}}=\frac{2^7\cdot3}{2^7\cdot2^4}=\frac{3}{2^4}=\frac{3}{16}\)
2. Tìm x
\(8^x:4^x=4\Rightarrow\left(8:4\right)^x=4\Rightarrow2^x=4\Rightarrow x=2\)
3. Ta có : \(222^{555}=\left(2\cdot111\right)^{555}=2^{555}\cdot111^{555}=\left(2^5\right)^{111}\cdot111^{555}=32^{111}\cdot111^{555}\)(1)
\(555^{222}=\left(5\cdot111\right)^{222}=5^{222}\cdot111^{222}=\left(5^2\right)^{111}\cdot111^{222}=25^{111}\cdot111^{222}\)(2)
Từ (1) và (2) ta thấy : 32 > 25 => 32111 > 25111 và 111555 > 111222 ( vì 555 > 222)
Vậy 222555 > 555222
-Vì (1/222)^333=(1/222)^3.111=(3/666)^111
(1/333)^222=(1/333)^2.111=(2/666)^111
-Vì 111=111 và 3/666>2/666
=))(1/222)^333>(1/333)^222
bài 1 :
b) (x-1/2 )2 = 0
<=> x - 1/2 = 0
<=> x = 0+ 1/2
<=> x = 1/2
c) ( x - 2 ) 2 = 1
<=> x -2 = 1
<=> x = 1 +2 = 3
d) ( 2x -1 )3 = -8
<=> ( 2x - 1) 3 = ( -2 ) 3
<=> 2x - 1 = -2
<=> 2x = -2+1 = -1
<=> x = -1/2
Bài 2 :
c) 32x-1=243
<=> 32x-1= 35
<=> 2x-1 = 5
<=> 2x = 6
<=> x = 6:2 = 3
Mk chỉ giải đc như vậy thôi
bạn thông cảm nhé !
Bài 1:
a) \(x^2-3=1\)
\(\Rightarrow x^2=1+3=4\)
\(\Rightarrow x=\pm2\)
b)\(2x^3+12=-4\)
\(\Rightarrow2x^3=-4-12=-16\)
\(\Rightarrow x^3=-8\)
\(\Rightarrow x=-2\)
c)\(\left(2x-3\right)^2=16\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-3=4\\2x-3=-4\end{matrix}\right.\Leftrightarrow}\left[{}\begin{matrix}x=\dfrac{7}{2}\\-\dfrac{1}{2}\end{matrix}\right.\)
a) \(x^2-3=1\Rightarrow x^2=4\Rightarrow x=\pm2\)
b) \(2x^3+12=-4\Rightarrow2x^3=-16\)
\(\Rightarrow x^3=-\dfrac{16}{2}=-8=-2^3\)
\(\Rightarrow x=-2\)
c) \(\left(2x-3\right)^2=16\)
\(\Rightarrow\left[{}\begin{matrix}2x-3=4\\2x-3=-4\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\dfrac{7}{2}\\x=-\dfrac{1}{2}\end{matrix}\right.\)
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