a) A =123 . 137137

A = 123 . ( 137 . 1001 )

A = ( 123 . 137 ) . 1001

B = 137 . 123123

B = 137 . ( 123 . 1001 )

B = ( 137 . 123 ) . 1001

=> A = B

b) C = 199 . 201

C = 199 . ( 200 + 1 )

C = 199 . 200 + 199 . 1

D = ( 199 + 1 ) . 200

D = 199 . 200 + 1 . 200

Có 199 . 200 = 199 . 200. Mà 199 . 1 < 200 . 1

=> C < D

a, Ta có :

A = 123 . 137137 

A = 123 . ( 137 . 101 )

A = 137 . 101 . 123

B = 137 . 123123

B = 137 . ( 123 . 101 )

B = 123 . 101 . 137

=> A = B

b, Ta có :

C = 199 . 201

C = 199 . ( 200 + 1 )

C = 199 . 200 + 199 . 1 

D = 200 . 200

D = ( 199 + 1 ) . 200

D = 199 . 200 + 1 . 200

=> C < D 

Để mk trả lời cụ thể hơn:

A = 200x199 + 200 

B = 200 x 199 + 199

Nên => A > B 

K mk nha, mk nhanh và đúng nè

200 nhan 200 bé hon199 nhan 201

A > B

200 x 200 lớn hơn 199x201

K mk nha

Ta co:

A = 199 x (200 + 1)

= 199 x 1 + 199 x 200 = 199 x 200 + 199

B = 200 x (199 + 1)

= 200 x 199 + 200 x 1 = 200 x 199 + 200

Vi 199 x 200 + 199 < 200 x 199 + 200

Nen A < B

kết bạn với mình nha

a) Ta có: A = 123 x 123 = 123 x ( 124 - 1 ) = 123 x 124 - 123
               B = 121 x 124 = ( 123 - 2 ) x 124 = 123 x 124 - 248
Suy ra: 123 x 124 - 123 > 123 x 124 - 248 hay A > B

b) Ta có: C = 123 x 137137 = 123 x 137 x 1001 = 137 x 123 x 1001
               D = 137 x 123123 = 137 x 123 x 1001
Suy ra: C = D

c) Ta có: E = 2015 x 2017 = 2015 x ( 2016 + 1 ) = 2015 x 2016 + 2015
               F = 2016 x 2016 = ( 2015 + 1 ) x 2016 = 2015 x 2016 + 2016
Suy ra: 2015 x 2016 + 2015 < 2015 x 2016 + 2016 hay E < F 
 

a) \(\frac{47}{32}>\frac{36}{46}\)Vì phân số \(\frac{47}{32}>1;\frac{36}{46}< 1\)nên \(\frac{47}{32}>\frac{36}{46}\)

b) \(\frac{199}{200}< \frac{200}{201}\)Vì \(\frac{199}{200}=\frac{199.201}{200.201};\frac{200}{201}=\frac{200.200}{201.200}\)

ta so sánh 199.201 và 200.200 

199.201 = 199.(200+1) = 199.200+199

200.200 = 200.(199+1) = 200.199+200

Vì 199.200 + 199 < 200.199+200 nên \(\frac{199}{200}< \frac{200}{201}\)

c) \(\frac{2012.2010}{2011.2011}=\frac{\left(2011+1\right).2010}{2011.\left(2010+1\right)}=\frac{2011.2010+2010}{2011.2010+2011}\)

\(\frac{2013.2009}{2014.2008}=\frac{2013.\left(2008+1\right)}{\left(2013+1\right).2008}=\frac{2013.2008+2013}{2013.2008+2008}\)

ta so sánh : \(\frac{2010}{2011}< \frac{2013}{2008}\) vì \(\frac{2010}{2011}< 1;\frac{2013}{2008}>1\)

\(^{A=\left(200+1\right).199=200.199+199

A=201.199=(200+1).199=200.199+199

B=200.200=(199+1).200=199.200+200

Vì 200.199+199<199.200+200 nên A<B

A= 201*199 = ( 200+1) * ( 200 - 1) = 200 *200-1 > B = 200*200 

\(a,\dfrac{199}{200}=1-\dfrac{1}{200};\dfrac{200}{201}=1-\dfrac{1}{201}\\ Vì:\dfrac{1}{200}>\dfrac{1}{201}\\ \Rightarrow1-\dfrac{1}{200}< 1-\dfrac{1}{201}\\ Vậy:\dfrac{199}{200}< \dfrac{200}{201}\\ b,\dfrac{2001}{2002}=1-\dfrac{1}{2002};\dfrac{2002}{2003}=1-\dfrac{1}{2003}\\ Vì:\dfrac{1}{2002}>\dfrac{1}{2003}\Rightarrow1-\dfrac{1}{2002}< 1-\dfrac{1}{2003}\\ Vậy:\dfrac{2001}{2002}< \dfrac{2002}{2003}\)

\(c,\dfrac{2021}{2020}=1+\dfrac{1}{2020};\dfrac{2020}{2019}=1+\dfrac{1}{2019}\\ Vì:\dfrac{1}{2020}< \dfrac{1}{2019}\\ Nên:1+\dfrac{1}{2020}< 1+\dfrac{1}{2019}\\ Vậy:\dfrac{2021}{2020}< \dfrac{2020}{2019}\\ d,\dfrac{199}{198}=1+\dfrac{1}{198};\dfrac{200}{199}=1+\dfrac{1}{199}\\ Vì:\dfrac{1}{198}>\dfrac{1}{199}\\ Nên:1+\dfrac{1}{198}>1+\dfrac{1}{199}\\ Vậy:\dfrac{199}{198}>\dfrac{200}{199}\)