\(15x=10y=6z\)

\(\Rightarrow\dfrac{x}{2}=\dfrac{y}{3}=\dfrac{z}{5}\)

Áp dụng t/c dtsbn:

\(\dfrac{x}{2}=\dfrac{y}{3}=\dfrac{z}{5}=\dfrac{x+y+z}{2+3+5}=\dfrac{20}{10}=2\)

\(\Rightarrow\left\{{}\begin{matrix}x=2.2=4\\y=2.3=6\\z=2.5=10\end{matrix}\right.\)

minh hoc lop 10 ket ban voi minh nhe

a) 15x = -75
\(\Rightarrow\)x = - 75 : 15
\(\Rightarrow\)x = - 5
b) 3|x| = 18
\(\Rightarrow\)|x| = 18 : 3 
\(\Rightarrow\)|x| = 6
\(\orbr{\begin{cases}x=6\\x=-6\end{cases}}\)

a,15x=-75

   x=-75.15

   x=-1125

b,3/x/=18

=>3x=18=>x=6

hoac 3x=-18=>x=-6

\(15x=-10y\) => \(\frac{x}{-10}=\frac{y}{15}\) => \(\frac{x}{-2}=\frac{y}{3}\)

 \(-10y=6z\) => \(\frac{y}{6}=\frac{z}{-10}\) => \(\frac{y}{3}=\frac{z}{-5}\)

=> \(\frac{x}{2}=\frac{y}{-3}=\frac{z}{5}\)

=> \(\left(\frac{x}{2}\right)^3=\left(\frac{y}{-3}\right)^3=\left(\frac{z}{5}\right)^3=\frac{xyz}{2.-3.5}=\frac{-30000}{-30}=1000\)

=> x = 20

y = -30

z = 50

Chúc bạn làm bài tốt

\(15x=-10y=6z\Rightarrow\frac{15x}{30}=\frac{-10y}{30}=\frac{6z}{30}\)

\(\Rightarrow\)\(\frac{x}{2}=\frac{y}{-3}=\frac{z}{5}\)

Đặt   \(\frac{x}{2}=\frac{y}{-3}=\frac{z}{5}=n\)

\(\Rightarrow x=2n,y=-3n,z=5n\)

\(\Rightarrow xyz=2n.-3n.5n\)

\(=-30n^3=-30000\Rightarrow n^3=-1000=-10^3\)

\(\Rightarrow n=-10\)

\(B=-x^2-10y^2+6xy-2x+10y-3\)

\(=-x^2-9y^2-1+6xy-2x+6y-y^2+4y-4+2\)

\(=-\left(x-3y+1\right)^2-\left(y-2\right)^2+2\le2\)

Dấu \(=\)khi \(\hept{\begin{cases}x-3y+1=0\\y-2=0\end{cases}}\Leftrightarrow\hept{\begin{cases}x=5\\y=2\end{cases}}\).

15x = -10y = 6z

<=> \(\frac{15x}{30}=\frac{-10y}{30}=\frac{6z}{30}\) 

<=> \(\frac{x}{2}=\frac{y}{-3}=\frac{z}{5}\)

Đặt \(\frac{x}{2}=\frac{y}{-3}=\frac{z}{5}=k\Rightarrow\hept{\begin{cases}x=2k\\y=-3k\\z=5k\end{cases}}\)

Ta có: xyz = -30000

=> 2k.(-3k).5k = -30000

=> -30k³ = -30000

=> k³ = 1000

=> k = 10

=> x = 20, y = -30, z = 50

Vì  15x = -10y = 6z => \(\frac{15x}{30}=\frac{-10y}{30}=\frac{6z}{30}\)  => \(\frac{x}{2}=\frac{-y}{3}=\frac{z}{5}\)

Đặt : \(\frac{x}{2}=\frac{-y}{3}=\frac{z}{5}=k\), ta có : x = 2k ; y = (-3).k ; x = 5k

=> x.y.z = 2   .k. ( -3 ). k.5.k = -30.k³ = -30000

=> k³ = 1000 => k = 10 => x = 10. 2 = 20

                                     => y = 10. ( - 3 ) = -30

                                      => z = 10.5 = 50

Ta có : 15x = 6z

=> x = 6/15z

-10y = 6z

=>  y= -3/5z

=> xyz = -30000

<=> (6/15z) . (-3/5z) . z = -30000

<=> z^3 .( -6/25) = -30000

<=> z^3       = 125000

<=> z   = 50

=> y = -30

=> x = 20

20 k mk nhe !

Ta có : 

15x = -10y

=> 3.x = -2.y => x/-2 = y/3 [1]

-10y = 6.z

=> -5.y = 3.z => y/3 = z/-5 [2]

Từ [1] và [2] => x/-2 = y/3 = z/-5

Đặt x/-2= y/3 = z/-5 = k

=> x= -2k ; y= 3k  ; z= -5k

=> xyz = 30. k^3 = 30000 => k^3 = 1000 => k = 10

=> x= -20 ; y = 30 ; z= -50

Vậy x= -20 ; y= 30 ; z= -50