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Sửa đề: \(\dfrac{74-x}{26}+\dfrac{75-x}{25}+\dfrac{76-x}{24}+\dfrac{77-x}{23}+\dfrac{78-x}{22}=-5\)Ta có: \(\dfrac{74-x}{26}+\dfrac{75-x}{25}+\dfrac{76-x}{24}+\dfrac{77-x}{23}+\dfrac{78-x}{22}=-5\)

\(\Leftrightarrow\dfrac{74-x}{26}+1+\dfrac{75-x}{25}+1+\dfrac{76-x}{24}+1+\dfrac{77-x}{23}+1+\dfrac{78-x}{22}+1=0\)

\(\Leftrightarrow\dfrac{100-x}{26}+\dfrac{100-x}{25}+\dfrac{100-x}{24}+\dfrac{100-x}{23}+\dfrac{100-x}{22}=0\)

\(\Leftrightarrow\left(100-x\right)\left(\dfrac{1}{26}+\dfrac{1}{25}+\dfrac{1}{24}+\dfrac{1}{23}+\dfrac{1}{22}\right)=0\)

mà \(\dfrac{1}{26}+\dfrac{1}{25}+\dfrac{1}{24}+\dfrac{1}{23}+\dfrac{1}{22}>0\)

nên 100-x=0

hay x=100

Vậy: S={100}

9 tháng 2 2021

Ta có : \(\dfrac{74-x}{26}+\dfrac{75-x}{25}+\dfrac{76-x}{24}+\dfrac{77-x}{23}+\dfrac{78-x}{22}=-5\)

\(\Leftrightarrow\dfrac{74-x}{26}+\dfrac{75-x}{25}+\dfrac{76-x}{24}+\dfrac{77-x}{23}+\dfrac{78-x}{22}+5=0\)

\(\Leftrightarrow\dfrac{74-x}{26}+1+\dfrac{75-x}{25}+1+\dfrac{76-x}{24}+1+\dfrac{77-x}{23}+1+\dfrac{78-x}{22}+1=0\)

\(\Leftrightarrow\dfrac{100-x}{26}+\dfrac{100-x}{25}+\dfrac{100-x}{24}+\dfrac{100-x}{23}+\dfrac{100-x}{22}=0\)

\(\Leftrightarrow\left(100-x\right)\left(\dfrac{1}{26}+\dfrac{1}{25}+\dfrac{1}{24}+\dfrac{1}{23}+\dfrac{1}{22}\right)=0\)

Thấy : \(\dfrac{1}{26}+\dfrac{1}{25}+\dfrac{1}{24}+\dfrac{1}{23}+\dfrac{1}{22}\ne0\)

\(\Rightarrow100-x=0\)

\(\Leftrightarrow x=100\)

Vậy ...

 

 

 

 

 

 

 

 

 

 

 

 

 

18 tháng 6 2016

Bạn cho mũ vào đi

AH
Akai Haruma
Giáo viên
2 tháng 12 2023

Bài 1:

a. $=(-25)(-4)(-35)=100(-35)=-3500$

b. $=16-10=6$

c. $=180-(-16)-(-36)=180+16+36=232$

d. $=250-200:[1(-3)^2+(-8)]$

$=250-200:(9-8)=250-200=50$

AH
Akai Haruma
Giáo viên
2 tháng 12 2023

2.

$60+2(12-x)=-48$

$2(12-x)=60-(-48)=60+48=108$

$12-x=108:2=54$

$x=12-54=-42$
 

AH
Akai Haruma
Giáo viên
29 tháng 11 2023

Bài 1:

a. $=(-25)(-4)(-35)=100(-35)=-3500$

b. $=16-10=6$

c. $180-(-16)-(-36)=180+16+36=196+36=232$

d. $=250-200:[2000.(-3).2-6]$

$=250-200:[2000.(-6)+(-6)]$

$=250-200:[(-6)(2000+1)]=250-200[(-6).2001]$

$=250+200.6.2001=250+2401200=2401450$

AH
Akai Haruma
Giáo viên
29 tháng 11 2023

Bài 2:

$60+2(12-x)=-48$

$2(12-x)=-48-60=-108$
$12-x=-108:2=-54$

$x=12-(-54)=66$

12 tháng 12 2021

Bài 1:

\(a,A=\left(2+2^2\right)+\left(2^3+2^4\right)+...+\left(2^{2009}+2^{2010}\right)\\ A=\left(1+2\right)\left(2+2^3+...+2^{2009}\right)=3\left(2+...+2^{2009}\right)⋮3\\ A=\left(2+2^2+2^3\right)+...+\left(2^{2008}+2^{2009}+2^{2010}\right)\\ A=\left(1+2+2^2\right)\left(2+...+2^{2008}\right)=7\left(2+...+2^{2008}\right)⋮7\)

\(b,\left(\text{sửa lại đề}\right)B=\left(3+3^2\right)+\left(3^3+3^4\right)+...+\left(3^{2009}+3^{2010}\right)\\ B=\left(1+3\right)\left(3+3^3+...+3^{2009}\right)=4\left(3+3^3+...+3^{2009}\right)⋮4\\ B=\left(3+3^2+3^3\right)+...+\left(3^{2008}+3^{2009}+3^{2010}\right)\\ B=\left(1+3+3^2\right)\left(3+...+3^{2008}\right)=13\left(3+...+3^{2008}\right)⋮13\)

12 tháng 12 2021

Bài 2:

\(a,\Rightarrow2A=2+2^2+...+2^{2012}\\ \Rightarrow2A-A=2+2^2+...+2^{2012}-1-2-2^2-...-2^{2011}\\ \Rightarrow A=2^{2012}-1>2^{2011}-1=B\\ b,A=\left(2020-1\right)\left(2020+1\right)=2020^2-2020+2020-1=2020^2-1< B\)

23 tháng 6 2015

\(\frac{74-x}{26}+\frac{75-x}{25}+\frac{76-x}{24}+\frac{77-x}{23}+\frac{78-x}{22}=-5\)

\(\frac{74-x}{26}+1+\frac{75-x}{25}+1+\frac{76-x}{24}+1+\frac{77-x}{23}+1+\frac{78-x}{22}=-5+5\)

\(\frac{74-x}{26}+\frac{26}{26}+\frac{75-x}{25}+\frac{25}{25}+\frac{76-x}{24}+\frac{24}{24}+\frac{77-x}{23}+\frac{23}{23}+\frac{78-x}{22}+\frac{22}{22}=0\)

\(\frac{100-x}{26}+\frac{100-x}{25}+\frac{100-x}{24}+\frac{100-x}{23}+\frac{100-x}{22}=0\)

\(\left(100-x\right)\left(\frac{1}{26}+\frac{1}{25}+\frac{1}{24}+\frac{1}{23}+\frac{1}{22}\right)=0\)

=>100-x=0    ( \(\left(\frac{1}{26}+\frac{1}{25}+\frac{1}{24}+\frac{1}{23}+\frac{1}{22}\right)\ne0\))

x=100

hahaha

23 tháng 6 2015

Cộng 1 vào mỗi hạng tử trong vế trái là dc

71 + 72 + 73 + 74 + 75 + 76 + 77 + 78 + 79

= ( 71 + 79 ) + ( 72 + 78 ) + ( 73 + 77 ) + ( 74 + 76 ) + 75

=     150           +           150              +      150                +          150           +         75

=                                       150        x          4         +     75 

=                                                   600       +      75

=                                                         675

Tìm x :

X x 7 + X x 2 = 108 

X  x ( 7 + 2 ) =  108

X  x    9         =   108

X                   =   108 : 9

X                   =      12

16 tháng 9 2018

     

  \(71+72+73+74+75+76+77+78+79\)

\(=\left(71+79\right)+\left(72+78\right)+\left(73+77\right)+\left(74+76\right)+75\)

\(=150+150+150+150+75\)

\(=600+75\)

\(=675\)

\(X\)x\(7+X\)x\(2=108\)

   \(X\)x\(\left(7+2\right)=108\)

                  \(X\)x\(9=108\)

                          \(X=108:9\)

                         \(X=12\)

                 Vậy \(X=12\)

72, Let’s go to the cinema tonight.Shall …………………………………73, What is your weight?How …………………………………………………………74, What a lovely cat!How………………………………………………………………75, 1, Nam will be eighteen next month.It will be …………………………………………………………76, When is your birthday?What is …………………………………………………………77, Where were you born?What is …………………………………………………………78, Hoang will be eighteen next month.It will be …………………………………………………………79, It takes me two hours to get to Hanoi by motorbike.I spend …………………………………………………………80, My...
Đọc tiếp

72, Let’s go to the cinema tonight.

Shall …………………………………

73, What is your weight?

How …………………………………………………………

74, What a lovely cat!

How………………………………………………………………

75, 1, Nam will be eighteen next month.

It will be …………………………………………………………

76, When is your birthday?

What is …………………………………………………………

77, Where were you born?

What is …………………………………………………………

78, Hoang will be eighteen next month.

It will be …………………………………………………………

79, It takes me two hours to get to Hanoi by motorbike.

I spend …………………………………………………………

80, My house is smaller than his one.

His house ………………………………………………………

81, She is able to speak English to her teacher.

She can …………………………………………………………

82, The black car is cheaper than the red one

 

The red car ……………………………………………………………………

3
4 tháng 8 2021

72, Let’s go to the cinema tonight.

Shall ………………… we go to the cinema tonight?………………

73, What is your weight?

How ……heavy are you?……………………………………………………

74, What a lovely cat!

How…………………………  lovely the cat is!……………………………………

75, 1, Nam will be eighteen next month.

It will be ………………  Nam's eighteenth birthday next month.…………………………………………

76, When is your birthday?

What is ………………… your date of birth?………………………………………

77, Where were you born?

What is …………………… your birthplace?……………………………………

78, Hoang will be eighteen next month.

It will be ………………… Hoang's eighteenth birthday next month.………………………………………

79, It takes me two hours to get to Hanoi by motorbike.

I spend …………………… two hours getting to Hanoi by motorbike.……………………………………

80, My house is smaller than his one.

His house ……… is bigger than my house.………………………………………………

81, She is able to speak English to her teacher.

She can ……………… speak English to her teacher.…………………………………………

82, The black car is cheaper than the red one

 

 

The red car ………………… is more expensive than the black one…………………………………………………

 

4 tháng 8 2021

72, Let’s go to the cinema tonight.

 Shall we go to the cinema tonight?………………………………… 73, What is your weight? How heavy are you………………………………………………………… 74, What a lovely cat! How lovely the cat is……………………………………………………………… 75, 1, Nam will be eighteen next month. It will be Nam's eighteenth birthday next month………………………………………………………… 76, When is your birthday? What is your birthday'day?………………………………………………………… 77, Where were you born? What is your hometown………………………………………………………… 78, Hoang will be eighteen next month. It will be Hoang's eighteenth birthday next month………………………………………………………… 79, It takes me two hours to get to Hanoi by motorbike. I spend 2 hours getting to HN by bike………………………………………………………… 80, My house is smaller than his one. His house is bigger than my……………………………………………………… 81, She is able to speak English to her teacher. She can speak English to her teacher………………………………………………………… 82, The black car is cheaper than the red one The red car is more expensive than the black one……………………………………………………………………