a) \(\left|1-x\right|+\left|y-\frac{2}{3}\right|+\left|x+z\right|=0\)

\(\Leftrightarrow\hept{\begin{cases}1-x=0\\y-\frac{2}{3}=0\\x+z=0\end{cases}\Leftrightarrow\hept{\begin{cases}x=1-0=1\\y=0+\frac{2}{3}=\frac{2}{3}\\z=0-1=-1\end{cases}}}\)

Vậy \(x=1,y=\frac{2}{3},z=-1\)

b) \(\left|\frac{1}{4}-x\right|+\left|x+y+z\right|+\left|\frac{2}{3}+y\right|=0\)

\(\Leftrightarrow\hept{\begin{cases}\frac{1}{4}-x=0\\x+y+z=0\\\frac{2}{3}+y=0\end{cases}\Leftrightarrow\hept{\begin{cases}x=\frac{1}{4}-0=\frac{1}{4}\\x+y+z=0\\y=0+\frac{2}{3}=\frac{2}{3}\end{cases}\Leftrightarrow}\hept{\begin{cases}x=\frac{1}{4}\\z=0-\frac{1}{4}-\frac{2}{3}=\frac{-11}{12}\\y=\frac{2}{3}\end{cases}}}\)

Vậy \(x=\frac{1}{4},y=\frac{-11}{12},z=\frac{2}{3}\)

\(\left(x-15\right)\left(y+12\right)\left(z-3\right)=0\)

=>\(\left[{}\begin{matrix}x-15=0\\y+12=0\\z-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=15\\y=-12\\z=3\end{matrix}\right.\)

TH1: x=15

x+1=y+2=z+3

=>y+2=z+3=15+1=16

=>y=16-2=14;z=16-3=13

TH2: y=-12

x+1=y+2=z+3

=>x+1=z+3=-12+2=-10

=>x=-10-1=-11; z=-10-3=-13

TH3: z=3

x+1=y+2=z+3

=>x+1=y+2=3+3=6

=>x=6-1=5; y=6-2=4

Bài 2: 

b: x=12; y=80

làm hộ mik cho

a) Ap dụng tích chất dãy tỉ số = nhau

Ta có:x/2=y/3=x+y/5+7=15/15=1

x/2=1=> x=2

y/3=1=> y=3

x + x : 0,2 = 1,35
x * 1 + x * 5 = 1,35
x * ( 1 + 5 ) = 1,35
x * 6 = 1,35
x = 1,35 : 6
x = 0,225

hok tốt nha ^_^

\(\frac{x}{2}=\frac{y}{3}\)

Áp dung tính chất của dãy tỉ số bằng nhau ta có'

\(\frac{x}{2}=\frac{y}{3}=\frac{x+y}{2+3}=\frac{15}{5}=3\)

=>

x = 3 .2=6

y =3.3 =9

a) (3^x+1 + 3^x) : 2 = 18

3^x.(3+1) = 36

3^x = 9 = 3²

=> x= 2

b) (x+3)² + (y-5)² = 0

mà \(\left(x+3\right)^2\ge0;\left(y-5\right)^2\ge0.\)

=> x = - 3; y = 5