a) y : 4/11 x 3/5 = 27/4

y : 4/11 = 27/4 : 3/5

y : 4/11 = 45/4

y = 45/4 x 4/11

y = 45/11

b) y + 7/2 - 5/9 = 14/3

y + 7/2 = 14/3 + 5/9

y + 7/2 = 47/9

y = 47/9 - 7/2

y = 31/18

a) y : 4/11 x 3/5 = 27/4

y : 4/11 = 27/4 : 3/5

y : 4/11 = 45/4

y = 45/4 x 4/11

y = 45/11
b) y + 7/2 - 5/9 = 14/3

y + 7/2 = 14/3 + 5/9

y + 7/2 = 47/9

y = 47/9 - 7/2

y = 31/18

\(\)a) \(y\) : \(\dfrac{4}{11}\) x \(\dfrac{3}{5}\) \(=\) \(\dfrac{27}{4}\)                   b) \(y\) \(+\) \(\dfrac{7}{2}\) \(-\) \(\dfrac{5}{9}\) \(=\) \(\dfrac{14}{3}\)

    \(y\) : \(\dfrac{4}{11}\)        \(=\) \(\dfrac{27}{4}:\dfrac{3}{5}\)                 \(y\) \(+\) \(\dfrac{7}{2}\)          \(=\) \(\dfrac{14}{3}\) \(+\) \(\dfrac{5}{9}\) 

    \(y\) : \(\dfrac{4}{11}\)        \(=\) \(\dfrac{45}{4}\)                       \(y\) \(+\) \(\dfrac{7}{2}\)           \(=\) \(\dfrac{47}{9}\)

    \(y\)                \(=\) \(\dfrac{45}{4}\) x \(\dfrac{4}{11}\)              \(y\)                    \(=\) \(\dfrac{47}{9}-\dfrac{7}{2}\)

    \(y\)                \(=\) \(\dfrac{45}{11}\)                      \(y\)                     \(=\) \(\dfrac{31}{18}\)

A nhé

Chọn A

bài 2 : a) \(\dfrac{a-1}{2}=\dfrac{b+3}{4}=\dfrac{c-5}{6}\)

áp dụng dảy tỉ số bằng nhau

ta có : \(\dfrac{5\left(a-1\right)-3\left(b+3\right)-4\left(c-5\right)}{5.2-3.4-4.6}\)

\(=\dfrac{5a-5-3b-9-4c+20}{10-12-24}=\dfrac{\left(5a-3b-4c\right)-5-9+20}{-26}\)

\(=\dfrac{46+6}{-26}=\dfrac{52}{-26}=-2\)

\(\Rightarrow\left\{{}\begin{matrix}\dfrac{a-1}{2}=-2\\\dfrac{b+3}{4}=-2\\\dfrac{c-5}{6}=-2\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}a-1=-4\\b+3=-8\\c-5=-12\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}a=-3\\b=-11\\c=-7\end{matrix}\right.\)

vậy \(a=-3;b=-11;c=-7\)

b) ta có : \(3a=2b\Leftrightarrow6a=4b=5c\Leftrightarrow\dfrac{6a}{2}=\dfrac{4b}{2}=\dfrac{5c}{2}\)

áp dụng dảy tỉ số bằng nhau

ta có \(\dfrac{-60a-60b+60c}{-10.2-15.2+12.2}=\dfrac{60\left(-a-b+c\right)}{-20-30+24}\)

\(=\dfrac{60\left(-52\right)}{-26}=\dfrac{-3120}{-26}=120\)

\(\Rightarrow\left\{{}\begin{matrix}\dfrac{6a}{2}=120\\\dfrac{4b}{2}=120\\\dfrac{5c}{2}=120\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}6a=240\\4b=240\\5c=240\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}a=40\\b=60\\c=48\end{matrix}\right.\)

vậy \(a=40;b=60;c=48\)

bai de wa sao phai lam cho met

a, y \(\times\) \(\dfrac{4}{3}\) = \(\dfrac{16}{9}\)

    y         =    \(\dfrac{16}{9}\) : \(\dfrac{4}{3}\)

    y         = \(\dfrac{4}{3}\)

b, ( y - \(\dfrac{1}{2}\)) + 0,5 = \(\dfrac{3}{4}\)

    y - 0,5 + 0,5 = \(\dfrac{3}{4}\)

   y                   = \(\dfrac{3}{4}\)

c, \(\dfrac{4}{5}-\dfrac{2}{5}y\) = 0,2

   0,8 - 0,4y = 0,2

           0,4y = 0,8 - 0,2

           0,4y  = 0,6

               y = 1,5

d, (y + \(\dfrac{3}{4}\)) \(\times\) \(\dfrac{5}{7}\) = \(\dfrac{10}{9}\)

    y + \(\dfrac{3}{4}\)           = \(\dfrac{10}{9}\) : \(\dfrac{5}{7}\)

   y + \(\dfrac{3}{4}\)            = \(\dfrac{14}{9}\)

y                    = \(\dfrac{14}{9}\) - \(\dfrac{3}{4}\)

 y                   =   \(\dfrac{29}{36}\)

e, y : \(\dfrac{5}{4}\)         = \(\dfrac{9}{5}\)  + \(\dfrac{1}{2}\)

   y : \(\dfrac{5}{4}\)         =   \(\dfrac{23}{10}\)

  y                =      \(\dfrac{23}{10}\)

  y               =   \(\dfrac{23}{8}\)

f, y \(\times\) \(\dfrac{1}{2}\) + \(\dfrac{3}{2}\) \(\times\) y   = \(\dfrac{4}{5}\)

   y \(\times\) ( \(\dfrac{1}{2}+\dfrac{3}{2}\))      =  \(\dfrac{4}{5}\)

   2y                       = \(\dfrac{4}{5}\)

    y                        = \(\dfrac{2}{5}\)

`a)`

`A=-4x^5y^3+6x^4y^3-3x^2y^3z^2+4x^5y^3-x^4y^3+3x^2y^3z^2-2y^4+22`

`A=(-4x^5y^3+4x^5y^3)+(6x^4y^3-x^4y^3)-(3x^2y^3z^2-3x^2y^3z^2)-2y^4+22`

`A=5x^4y^3-2y^4+22`

        `->` Bậc: `7`

`b)B-5y^4=A`

`=>B=A+5y^4`

`=>B=5x^4y^3-2y^4+22+5y^4`

`=>B=5x^4y^3+3y^4+22`

bài 1 : a,ta có 3/x-1 =4/y-2=5/z-3 =>  x-1/3=y-2/4=z-3/5 

áp dụng .... => x-1+y-2+z-3 / 3+4+5 = x+y+z-1-2-3/3+4+5 = 12/12=1

do x-1/3 = 1 => x-1 = 3 => x= 4 ( tìm y,z tương tự

Bài 1: 

a) Ta có: 3/x - 1 = 4/y - 2 = 5/z - 3 => x - 1/3 = y - 2/4 = z - 3/5 áp dụng ... =>x - 1 + y - 2 + z - 3/3 + 4 + 5 = x + y + z - 1 - 2 - 3/3 + 4 + 5 = 12/12 = 1 do x - 1/3 = 1 => x - 1 = 3 => x = 4 ( tìm y, z tương tự )

cũng dễ thôi

a) y × 2/5 + y × 3/5 = 5/7 

y x ( 2/5 + 3/5) = 5/7

y x 5/5 = 5/7

y x 1 = 5/7

y = 5/7 : 1

y = 5/7

b) y × 7/2 - y × 3/2 = 3/4

y x ( 7/2 - 3/2) = 3/4

y x 4/2 = 3/4

y x 2 = 3/4

y = 3/4 : 2

y = 3/4 x 1/2

y = 3/8

`a,yxx(2/5+3/5)=5/7`

`y xx1=5/7`

`y=5/7:1`

`y=5/7`

`b,y xx(7/2-3/2)=3/4`

`y xx2=3/4`

`y =3/4:2`

`y=3/2`