so sanh p/s sau :
A)3/-4 va -1/-4
B)15/17 va 25/27
ai dung cho 1 LIKE
So sanh cac so sau day 1 cach nhanh chong
A/ 3/4 va 115/14
B/ 2000/1999 a 1998//1999
C/ -17/234 va 1/1995
D/ 23/-15 va -17/-49
a) 3/4 < 1
115/14 > 1
=> 3/4 < 115/14
b) 2000/1999 > 1
1998/1999 < 1
=> 2000/1999>1998/1999
c)-17/234 < 0 , 1/1995 > 0
=> -17/234 < 1/1995
d) 23/-15 < 0 ; -17/-49>0
=> 23/-15 < -17/-49
so sanh cac phan so sau day bang cach hop li nhat
a}23/3 va 15/2
b 4/17 va 2/9
a) Ta có:
\(\frac{23}{3}=\frac{21+2}{3}=\frac{21}{3}+\frac{2}{3}=7+\frac{2}{3}\)
\(\frac{15}{2}=\frac{14+1}{2}=\frac{14}{2}+\frac{1}{2}=7+\frac{1}{2}\)
Lại có:\(1-\frac{2}{3}=\frac{1}{3}< 1-\frac{1}{2}=\frac{1}{2}\Rightarrow\frac{2}{3}>\frac{1}{2}\)
\(\Rightarrow\frac{23}{3}>\frac{15}{2}\)
a, 23/3 và 15/2
Ta có :
23/3 = 23x2/3x2 = 46/6. 15/2 = 15x3/2x3 = 45/6.
Vậy 46/6 > 45/6 nên 23/3 > 15/2.
b, 4/17 và 2/9.
Ta có :
4/17 = 4x9/17x9 = 36/153. 2/9 = 2x17/9x17 = 34/153.
Vậy 36/153 > 34/153 nên 4/17 > 2/9.
cho A=316+1/315+1
cho B=317+1/316+1
so sanh hai phan so A va B
So sanh A va B biet A=2010/2011+2011/2012+2012/2010 va B=1/3+1/4+1/5+....+1/17
Cho S = 1/11 + 1/12 + 1/13 + 1/14 + 1/15 + 1/16 + 1/17 + 1/18 + 1/19 + 1/20.
Hay so sanh S va 1/2
so sanh cac phan so sau;
a, 3/4 va 4/5
b, 7/12 va 17/36
c, 5/6 va 6/7 va 7/8
a, Ta có : 1 - 3/4 = 1/4 ; 1 - 4/5 = 1/5
Vì 1/4 > 1/5 nên 3/4 < 4/5
b, Ta có :7/12 = 21/36
Vì 21/36 > 17/36 nên 7/12 > 17/36
c, Ta có:
1 - 5/6 = 1/6
1 - 6/7 = 1/7
1 - 7/8 = 1/8
Vì 1/6 > 1/7 > 1/8 nên 5/6 < 6/7 < 7/8
so sanh cac so huu ti sau:
a.x=-3/5 va y=2/-3
b.x=35/84 va y=8/15
c.x=-5/4 va y=-3/8
d.x=-3/100 va y=2/3
e.x=8/9 va y=19/18
f.x=1250/1251 va y=25/24
So sanh cac phan so sau :
a, 7/11 va 17/23 b, 12/48 va 13/47 c, 25/30 va 75/97
d, 23/47 va 24/45 e, 34/43 va 35/42 s, 23/48 va 47/92
1) Tim x
3^x +3^x+1 +3^x+2=351
2) So sanh
a)25^15 va 8^10×3^30
b(0,1)^10 va (0,3)^20
\(1)\) \(3^x+3^{x+1}+3^{x+2}=351\)
\(\Leftrightarrow\)\(3^x.1+3^x.3+3^x.3^2=351\)
\(\Leftrightarrow\)\(3^x\left(1+3+3^2\right)=351\)
\(\Leftrightarrow\)\(3^x.13=351\)
\(\Leftrightarrow\)\(3^x=\frac{351}{13}\)
\(\Leftrightarrow\)\(3^x=27\)
\(\Leftrightarrow\)\(3^x=3^3\)
\(\Leftrightarrow\)\(x=3\)
Vậy \(x=3\)
Chúc bạn học tốt ~
\(2)\)
\(a)\) Ta có :
\(25^{15}=\left(5^2\right)^{15}=5^{2.15}=5^{30}\)
\(8^{10}.3^{30}=\left(2^3\right)^{10}.3^{30}=2^{30}.3^{30}=\left(2.3\right)^{30}=6^{30}\)
Vì \(5^{30}< 6^{30}\) nên \(25^{15}< 8^{10}.3^{30}\)
Vậy \(25^{15}< 8^{10}.3^{30}\)
\(b)\) Ta có :
\(\left(0,3\right)^{20}=\left[\left(0,3\right)^2\right]^{10}=\left(0,09\right)^{10}\)
Vì \(\left(0,1\right)^{10}>\left(0,09\right)^{10}\) nên \(\left(0,1\right)^{10}>\left(0,3\right)^{20}\)
Vậy \(\left(0,1\right)^{10}>\left(0,3\right)^{20}\)
Chúc bạn học tốt ~