x - 1/3 = 1/4 . x 

-1/3 = 1/4 .x -x 

-1/3 = x . [1/4 -1 ]

-1/3 = x . -3/4

x . -3/4 = -1/3 

x = -1/3 ; -3/4

x = 4/9

\(\left(4^2\right).x-\left(3^2\right).x=49\)

\(x\left(4^2-3^2\right)=49\)

\(x\left(16-9\right)=49\)

\(x.7=49\)

\(\Rightarrow x=49:7=7\)

là  bàng x(4^2-3^2) =x (7)=49

suy ra x = 49:7 =7 

Vậu x =7 

hk tốt

1. may / it / rain / tomorrow

it may rain tomorrow

2. you / do / could / a / me / favor

could you do me a favor?

3. you / could / form / for / me / fill / in / this?

could you fill in this form for me?

4. we / should/do/what/to/help/street/children?

what should we do to help street children?

5. out/this/please/application/fill/form?

please fill out this application form.

6. suggest/I/we/for/the/poor/should/funds/raise

I suggest we should raise funds for the poor

7. by/elderly/can/them/shopping/people/we/for/doing/help

we can help elderly people by doing shopping for them

8. carry/my/bags/can/me/you/help?

can you help me carry my bags?

1. may / it / rain / tomorrow

=> It may rain tomorrow.

2. you / do / could / a / me / favor

=> Could you do me a favor?

3. you / could / form / for / me / fill / in / this?

=> Could you fill in this form for me?

4. we / should/do/what/to/help/street/children?

=> What should we do to help street children?

5. out/this/please/application/fill/form?

=> Please fill out this application form.

6. suggest/I/we/for/the/poor/should/funds/raise

=> I suggest we should raise funds for the poor.

7. by/elderly/can/them/shopping/people/we/for/doing/help

=> We can help elderly people by doing shopping for them.

8. carry/my/bags/can/me/you/help?

=> Can you help me carry my bags?

Đặt \(\sqrt{x+1}=a,\sqrt{x^2-x+1}=b\left(a\ge0,b\ge\dfrac{1}{2}\right)\)

\(Pt\Leftrightarrow2a^2+2b^2-5ab=0\Leftrightarrow\left(2a-b\right)\left(a-2b\right)=0\)

đây nà bạn

\(\frac{x+4}{2007}+\frac{x+8}{2003}=\frac{x+1}{2010}=\frac{x+3}{2008}\)

\(\Leftrightarrow\frac{x+4}{2007}=\frac{x+1}{2010}\)

\(\Leftrightarrow\left(x+4\right)2010=\left(x+1\right)2007\)

\(\Leftrightarrow2010x+8040=2007x+2007\)

\(\Leftrightarrow2010x-2007x=2007-8040\)

\(\Leftrightarrow3x=-6033\)

\(\Leftrightarrow x=-2011\)

\(\frac{x+4}{2007}+\frac{x+8}{2003}=\frac{x+1}{2010}+\frac{x+3}{2008}\)

=>\(\left(\frac{x\text{+4}}{2007}+1\right)+\left(\frac{x+8}{2003}+1\right)=\left(\frac{x+1}{2010}+1\right)+\left(\frac{x+3}{2008}+1\right)\)

=>\(\frac{x+2011}{2007}+\frac{x+2011}{2003}=\frac{x+2011}{2010}+\frac{x+2011}{2008}\)

=>\(\frac{x+2011}{2007}+\frac{x+2011}{2003}-\frac{x+2011}{2010}-\frac{x+2011}{2008}=0\)

=>\(x+2011\left(\frac{1}{2007}+\frac{1}{2003}-\frac{1}{2010}-\frac{1}{2008}\right)=0\)

Mà \(\frac{1}{2007}+\frac{1}{2003}-\frac{1}{2010}-\frac{1}{2008}\ne0\)

=> x+2011=0

=>x=-2011

Vậy x = -2011

Ta có: \(\dfrac{3x-2y}{4}=\dfrac{2z-4x}{3}=\dfrac{4y-3z}{2}\)

\(\Rightarrow\dfrac{4\left(3x-2y\right)}{4.4}=\dfrac{3\left(2z-4x\right)}{3.3}=\dfrac{2\left(4y-3z\right)}{2.2}\)

\(\Rightarrow\dfrac{12x-8y}{16}=\dfrac{6z-12x}{9}=\dfrac{8y-6z}{4}\)

Áp dụng tính chất của dãy tỉ số bằng nhau, ta có:

\(\dfrac{12x-8y}{16}=\dfrac{6z-12x}{9}=\dfrac{8y-6z}{4}=\dfrac{12x-8y+6z-12x+8y-6z}{16+9+4}=0\)

\(\Rightarrow12x-8y=6z-12x=8y-6z=0\)

\(\Rightarrow\left\{{}\begin{matrix}12x=8y\\6z=12x\\8y=6z\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}3x=2y\\z=2x\\4y=3z\end{matrix}\right.\)

\(\Rightarrow\dfrac{x}{2}=\dfrac{y}{3},\dfrac{z}{2}=x,\dfrac{y}{3}=\dfrac{z}{4}\)

\(\Rightarrow\dfrac{x}{2}=\dfrac{y}{3},\dfrac{z}{4}=\dfrac{x}{2},\dfrac{y}{3}=\dfrac{z}{4}\)

\(\Rightarrow\dfrac{x}{2}=\dfrac{y}{3}=\dfrac{z}{4}\) (đpcm)

Tham khảo tại đây nhé: Câu hỏi của Phong Tuấn Đỗ - Toán lớp 7 | Học trực tuyến

4× (x+3)= 2 ×(x+1)+20

4 x + 12 = 2x + 2 + 20

2x = 10

x = 5

4.(x+3)=2.x+2+20

12+4x =2x+22

4x       =2x+10

2x       =10

x         =10:2

x         =5

Nhớ phải giữ lời hứa đó!

Học tốt!

Ta có: \(\frac{1+x}{3}=\frac{3+x}{5}\)

=> 5.(1+x) = 3.(3+1)

=> 5 + 5x = 9 + 3x

=> 5x - 3x = 9 - 5

=> 2x = 4

=> x = 2

Thế x = 2 vào \(\frac{1+x}{3}=\frac{8+2x}{3y}\)

Ta được: \(\frac{1+2}{3}=\frac{8+2.2}{3.y}\)= 1 = \(\frac{12}{3y}\)

=> y = 4

Vậy x = 2; y = 4

Nguyễn Huy TúTrương Hồng Hạnhsoyeon_Tiểubàng giảiHoàng Lê Bảo NgọcTrần Việt Linh

a: =>y=1,25x3,14=3,925

b: =>y:0,24=15-7,8=7,2

hay y=1,728

c: =>10y=36,7

hay y=3,67

d: =>6:y=1,5

hay y=4

e: =>4y+0,2y=44,1

=>4,2y=44,1

hay y=10,5