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13 tháng 12 2023

idk :)

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1
AH
Akai Haruma
Giáo viên
13 tháng 12 2023

Lời giải:

** Sửa đề: $A=\frac{ab}{(b-c)(c-a)}+\frac{bc}{(c-a)(a-b)}+\frac{ac}{(a-b)(b-c)}$

\(A=\frac{ab(a-b)+bc(b-c)+ac(c-a)}{(a-b)(b-c)(c-a)}=\frac{(a^2b+b^2c+c^2a)-(ab^2+bc^2+ca^2)}{-[(a^2b+b^2c+c^2a)-(ab^2+bc^2+ca^2)]}=-1\)

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1
AH
Akai Haruma
Giáo viên
13 tháng 12 2023

Lời giải:

$5x^2+5y^2+8xy-2x+2y+2=0$

$\Leftrightarrow 4(x^2+y^2+2xy)+(x^2-2x+1)+(y^2+2y+1)=0$

$\Leftrightarrow 4(x+y)^2+(x-1)^2+(y+1)^2=0$

Ta thấy: $(x+y)^2\geq 0; (x-1)^2\geq 0; (y+1)^2\geq 0$ với mọi $x,y$ 

Do đó để tổng của chúng bằng $0$ thì:

$(x+y)^2=(x-1)^2=(y+1)^2=0$

$\Rightarrow x=1; y=-1$

Khi đó:

$M=0^2+(1-2)^{2024}+(-1+1)^{2025}=0+1+0=1$

 

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1
13 tháng 12 2023

N = x² - 2xy + 3y² - 4y + 2023

= (x² - 2xy + y²) + (2y² - 4y) + 2023

= (x - y)² + 2(y² - 2y + 1) + 2021

= (x - y)² + 2(y - 1)² + 2021

Do (x - y)² ≥ 0 với mọi x, y ∈ R

⇒ (y - 1)² ≥ 0 với mọi y ∈ R

⇒ (x - y)² + 2(y - 1)² ≥ 0 với mọi x, y ∈ R

⇒ (x - y)² + 2(y - 1)² + 2021 > 0 với mọi x, y ∈ R

Vậy N luôn dương với mọi x, y ∈ R

12 tháng 12 2023

à

 

12 tháng 12 2023

dễ ý mà

 

Question 8: Choose the word that best fits each of the blanks in the following passage. Write your answers in the numbered blanks provided below the passage. (0) has been done as an example. (10point) Vietnamese generally shake hands when greeting and parting. Using both hands shows respect as does a (71)______bow of the head. In rural areas, elderly people do not extend their hand are greeted with   a bow.  Women are more (72)______to bow the head than to shake hands. Vietnamese names begin...
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Question 8: Choose the word that best fits each of the blanks in the following passage. Write your answers in the numbered blanks provided below the passage. (0) has been done as an example. (10point)

Vietnamese generally shake hands when greeting and parting. Using both hands shows respect as does a (71)______bow of the head. In rural areas, elderly people do not extend their hand are greeted with   a bow.  Women are more (72)______to bow the head than to shake hands. Vietnamese names begin with    the family name and are (73)_______by a given name. For example, in the name Nguyen Van Due, Nguyen is the family name. People address (74)_______by their given  names,  but add  a title that indicates their   perceived (75)_______to the other person. These titles are family related rather than professional. Among colleagues, for example, the (76)_______of the two might combine the given name with the title of Anh   ("Older Brother"). A(n) (77)______greeting combined with the given name and title is Xin chao ("Hello."). Classifiers for gender and familiarity are also combined with the greeting. In formal meetings, business cards are sometimes (78)_______on greeting.

Vietnamese people have a strong (79)______of hospitality and feel embarrassed if they cannot show their guests full respect by preparing for their  arrival. Therefore, it (80)______to visit someone without    having been invited. Gifts are not required, but are appreciated. Flowers, incense, or tea may be proper gifts for the hosts. Hosts also appreciate a small gift for their children or elderly parents

71. A. light                            B. slight                                 C. lightly                    D. lighted

72. A. possible                      B. capable                             C. probable               D. likely

73. A. continued                   B. chased                               C. followed               D. taken

74. A. each one                     B. one other                          C. one the other        D. one another

75. A. relation                       B. relationship                      C. relation                 D. relatives

76. A. younger                      B. most young                       C. youngest               D. young

77. A. easy                            B. basic                                  C. fundamentally      D. elementary

78. A. changed                      B. transferred                        C. reserved                D. exchanged

79. A. sense                           B. sensation                          C. sensitivity             D. sensible

80. A. inactive                      B. inaccurate                         C. inappropriate       D. inexact

1
12 tháng 12 2023

71. A. light                            B. slight                                 C. lightly                    D. lighted

72. A. possible                      B. capable                             C. probable               D. likely

73. A. continued                   B. chased                               C. followed               D. taken

74. A. each one                     B. one other                          C. one the other        D. one another

75. A. relation                       B. relationship                      C. relation                 D. relatives

76. A. younger                      B. most young                       C. youngest               D. young

77. A. easy                            B. basic                                  C. fundamentally      D. elementary

78. A. changed                      B. transferred                        C. reserved                D. exchanged

79. A. sense                           B. sensation                          C. sensitivity             D. sensible

80. A. inactive                      B. inaccurate                         C. inappropriate       D. inexact