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bài 4 : c1 \(3^{4000}\)và \(9^{2000}\)
\(\Leftrightarrow9^{2000}\Leftrightarrow\left(3^2\right)^2^{000}\Leftrightarrow3^{4000}\)
vì \(3^{4000}=3^{4000}\Leftrightarrow3^{4000}=9^{2000}\)
c2
ta có
\(3^{4000}=\left(3^4\right)^{1000}=81^{1000}\)
\(9^{2000}=\left(9^2\right)^{1000}=81^{1000}\)
vì \(81^{1000}=81^{1000}\Leftrightarrow3^{4000}=9^{2000}\)
bài 5
\(2^{332}< 2^{333}=\left(2^3\right)^{111}=8^{111}\)
\(3^{223}>3^{222}=\left(3^2\right)^{111}=9^{111}\)
vì \(8^{111}< 9^{111}\Leftrightarrow2^{332}< 3^{223}\)
3) M = 22010 - (22009 + 22008 + .... + 21 + 20)
Đặt N = 22009 + 22008 + .... + 21 + 20
=> 2N = 22010 + 22009 + .... + 22 + 21
=> 2N - N = (22010 + 22009 + .... + 22 + 21) - (22009 + 22008 + .... + 21 + 20)
=> N = 22010 - 1
Khi đó M = 22010 - (22010 - 1) = 1
4) C1 Ta có 34000 = (34)1000 = 811000 = (92)1000 = 92000
34000 = 92000
C2 Ta có : 34000 = (34)1000 = 811000 (1)
Lại có 92000 = (92)1000 = 811000 (2)
Từ (1) (2) => 34000 = 92000
5 Ta có 2332 < 2333 = (23)111 = 8111 < 9111 = (32)111 = 3222 < 3223
=> 2332 < 3223
2) Ta có n150 < 5225
=> (n5)75 < (53)75
=> n5 < 53
=> n5 < 125
Vì n là số nguyên lớn nhất => n = 2
1.
M = 22010 - ( 22009 + 22008 + ... + 21 + 20 )
đặt N = 22009 + 22008 + ... + 21 + 20
2N = 22010 + 22009 + ... + 22 + 21
2N - N = ( 22010 + 22009 + ... + 22 + 21 ) - ( 22009 + 22008 + ... + 21 + 20 )
N = 22010 - 20
Thay N vào ta được :
M = 22010 - ( 22010 - 20 )
M = 22010 - 22010 + 20
M = 20 = 1
2.
Ta có :
2332 < 2333 = ( 23 ) 111 = 8111
3223 > 3222 = ( 32 ) 111 = 9111
Vì 2332 < 8111 < 9111 < 3223
Bài 1:
Ta có: 200920=(20092)10=403608110 ; 2009200910=2009200910
Vì 403608110< 2009200910 => 200920< 2009200910
Bài 1:
Ta có:\(2009^{20}\)=\(2009^{10}\).\(2009^{10}\)
\(20092009^{10}\)=(\(\left(2009.10001\right)^{10}=2009^{10}.10001^{10}\)
Vì 2009<10001\(\Rightarrow2009^{20}< 20092009^{10}\)
ta có:
B=(2009^2010-2)/(2009^2011-2)<1
=>(2009^2010-2)/(2009^2011-2)<(2009^2010-2)+2011/(2009^2011-2)+2011=(2009^2010+2009)/(2009^2011+2009)
=[2009*(2009^2009+1)]/[2009*(2009^2010+1)]=(2009^2009+1)/(2009^2010+1)=A
Vậy A=B
Đúng thì !
\(C=\frac{\frac{1}{2008}-\frac{1}{2009}-\frac{1}{2010}}{\frac{5}{2008}-\frac{5}{2009}-\frac{5}{2010}}+\frac{\frac{2}{2007}-\frac{2}{2008}-\frac{2}{2009}}{\frac{3}{2007}-\frac{3}{2008}-\frac{3}{2009}}\)
\(=\frac{\frac{1}{2008}-\frac{1}{2009}-\frac{1}{2010}}{5.\left(\frac{1}{2008}-\frac{1}{2009}-\frac{1}{2010}\right)}+\frac{2.\left(\frac{1}{2007}-\frac{1}{2008}-\frac{1}{2009}\right)}{3.\left(\frac{1}{2007}-\frac{1}{2008}-\frac{1}{2009}\right)}\)
\(=\frac{1}{5}+\frac{2}{3}\)
\(=\frac{13}{15}\)
Đặt A = \(\frac{2009^{2009}+1}{2009^{2010}+1}\)
B = \(\frac{2009^{2010}-2}{2009^{2011}-2}\)
Do 20092010- 2 < 20092011- 2 => \(B<1\)
\(B=\frac{2009^{2010}-2}{2009^{2011}-2}<\frac{2009^{2010}-2+2011}{2009^{2011}-2+2011}=\frac{2009^{2010}+2009}{2009^{2011}+2009}=\frac{2009\left(1+2009^{2009}\right)}{2009\left(1+2009^{2010}\right)}\)
\(=\frac{2009^{2009}+1}{2009^{2010}+1}=A\Rightarrow\)B < A
bài 12 :
a,\(\left(x-\frac{1}{2}\right)^2=0\)
Mà: 02=0
=> \(\left(x-\frac{1}{2}\right)^2=0^2\)
\(\Rightarrow x-\frac{1}{2}=0\)
\(\Rightarrow x=\frac{1}{2}\)
b, \(\left(x-2\right)^2=1\)
Mà : 1=12
\(\Rightarrow\left(x-2\right)^2=1^2\)
=> x - 2 = 1
=> x = 3
c, \(\left(2x-1\right)^3=-8\)
\(\Rightarrow\left(2x-1\right)=-2\)
Vì -8 =-23
nên ...
=> 2x =-1
=> x=0.5
d.\(\left(x+\frac{1}{2}\right)^2=\frac{1}{16}\)
cái này cũng như mấy cái trên thôi
Bài 12:
a) \(\left(x-\frac{1}{2}\right)^2=0\)
\(\Rightarrow x-\frac{1}{2}=0\)
\(x=\frac{1}{2}\)
b) \(\left(x-2\right)^2=1\)
\(x-2=\pm1\)
- Nếu \(x-2=1\)
\(x=3\)
- Nếu \(x-2=-1\)
\(x=1\)
c) \(\left(2x-1\right)^3=-8\)
\(\Rightarrow2x-1=-2\)
\(2x=-1\)
\(x=-\frac{1}{2}\)
d) \(\left(x+\frac{1}{2}\right)^2=\frac{1}{16}\)
\(x+\frac{1}{12}=\pm\frac{1}{4}\)
- Nếu \(x+\frac{1}{12}=\frac{1}{4}\)
\(x=\frac{1}{6}\)
- Nếu \(x+\frac{1}{12}=-\frac{1}{4}\)
\(x=-\frac{1}{3}\)
Bài 13: có người làm rồi
Bài 14:
a) \(25^3\div5^2\)
\(=\left(5^2\right)^3\div5^2\)
\(=5^6\div5^2=5^4\)
b) \(\left(\frac{3}{7}\right)^{21}:\left(\frac{9}{49}\right)^6\)
\(=\left(\frac{3}{7}\right)^{21}:\left[\left(\frac{3}{7}\right)^2\right]^6\)
\(=\left(\frac{3}{7}\right)^{21}:\left(\frac{3}{7}\right)^{12}=\left(\frac{3}{7}\right)^9\)
c) \(3-\left(-\frac{6}{7}\right)^0+\left(\frac{1}{2}\right)^2:2\)
\(=3-1+\frac{1}{4}:2\)
\(=2+\frac{1}{8}=2\frac{1}{8}\)
\(2^{225}=\left(2^3\right)^{75}=8^{75}< 9^{75}=\left(3^2\right)^{75}=3^{150}\)
\(2^{2009}+2^{2008}+.......+2+1=b\)
\(\Rightarrow2b=2^{2010}+2^{2009}+.........+2^2+2\)
\(\Rightarrow2b-b=2^{2010}-1\Rightarrow b=2^{2010}-1\)
\(\Rightarrow A=2^{2010}-b=2^{2010}-\left(2^{2010}-1\right)=1\)