bạn ktra lại đề nhé 

a)100-9:(372:3.y-1)-14=83

<=>100-9:(124y-1)-14=83

<=>86-9:(124y-1)=83

<=>9:(124y-1)=3

<=>124y-1=3

<=>124y=4

<=>y=\(\frac{1}{31}\approx0,3223\)

b)7260-120:24.y+924=528,3

<=>8184-5y=528,3

<=>5y=7655,7

<=>y=1531,14

c)2000-52:(615:3:y-15)-14=1984

<=>1986-52:(205:y-15)=1984

<=>52:(205:y-15)=2

<=>205:y-15=26

<=>205:y=41

<=>y=5

d)y+y.1/3+5/18=7/18

<=>4/3y=1/9

<=>y=1/12

e)13/15-(5/21+y)7/12=7/10

<=>7/12.(5/21+y)=1/6

<=>5/36+7/12y=1/6

<=>7/12y=1/36

<=>y=1/21\(\approx\)0,4762

h)y+2.y+3.y+...+10.y=49,5

<=>55y=49,5

<=>y=0,9

i)y.(1975/8.9+1885/9.10+1755/10.11+1579/11.12)=1/24

<=>7991,364899y=1/24

<=>y=33/6329161

tích nha mỏi tay quá

ĐKXĐ: \(x\ne_-^+y;y\ne0\)

Từ PT thứ 2 ta có:\(\dfrac{96}{x-y}+\dfrac{72}{x-y}=\dfrac{24}{y}\)

<=>\(\dfrac{168}{x-y}=\dfrac{24}{y}\)

<=>\(\dfrac{168}{x-y}=\dfrac{168}{7y}\)

<=>x-y=7y

<=>x=8y

Thay x=8y vào PT thứ nhất:

\(\dfrac{96}{8y+y}+\dfrac{96}{8y-y}=14\)

<=>\(\dfrac{32}{3y}+\dfrac{96}{7y}=14\)

<=>32.7y+96.3y=294y²

<=>512y=294y²

<=>y=\(\dfrac{256}{147}\left(Doy\ne0\right)\)

=>x=8y=\(\dfrac{2048}{147}\)

Vậy...

x254n3jsm3,s3333

a: =25x100-150=2500-150=2350

c: \(=520:\left\{515\cdot25\right\}\)

=104/2575

Ta có

Do đó, hai đại lượng x và y không tỉ lệ thuận với nhau.

a) 5 + (-5) = 0

b) 71-52 = 19

c) 28 + (-82) = -64

d) 47 + (-30) = 17

e) (-41) + (-59) = -100

f) 75 + (-10) = 65

t) 26 - 43 = -17

y) 90 - 25 = 650

o) 72 + (-9) = 63

p) (-3) + 3 = 0

a, (-72).(15 - 49) + 15.(-56 + 72)

= -72 . 15 + 72.49  - 15.56 + 15.72

= (-72.15 + 15.72) + (72.49  - 15.56)

= 3528 - 84

= 2688

1b, 1532 + (-186) + (-1432) + (-14) + 123

= (1532 - 1432) - (186 + 14) + 123

= 100 - 200 + 123

= 223 - 200

= 23 

43.(53 - 81) + 53.(81 - 43)

= 43.53 - 81.43 + 53.81 - 53.43

= (43.53 - 53.43) + (81.53 - 81.43)

= 0 + 81.(53-43)

= 81.10

= 810

1/ \(\left\{{}\begin{matrix}\left(x-2\right)^{72}\ge0\\\left(y+1\right)^{70}\ge0\end{matrix}\right.\)

Mà \(\left(x-2\right)^{72}+\left(y+1\right)^{70}=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}\left(x-2\right)^{72}=0\\\left(y+1\right)^{70}=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x-2=0\\y+1=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=-1\end{matrix}\right.\)

Vậy ...

2/ \(\left\{{}\begin{matrix}\left|x+1\right|\ge0\\\left|y-3\right|\ge0\end{matrix}\right.\)

Mà \(\left|x+1\right|+\left|y-3\right|=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}\left|x+1\right|=0\\\left|y-3\right|=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=-1\\y=3\end{matrix}\right.\)

Vậy ...

3/ \(\left\{{}\begin{matrix}\left(2x-10\right)^{100}\ge0\\\left(x-y\right)^{102}\ge0\end{matrix}\right.\)

Mà \(\left(2x-10\right)^{100}+\left(x-y\right)^{102}=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}\left(2x-10\right)^{100}=0\\\left(x-y\right)^{102}=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}2x-10=0\\x-y=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=5\\y=5\end{matrix}\right.\)

Vậy ....

4/ \(\left\{{}\begin{matrix}\left|2x+8\right|\ge0\\\left|y+x\right|\ge0\end{matrix}\right.\)

Mà \(\left|2x+8\right|+\left|y+x\right|=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}\left|2x+8\right|=0\\\left|y+x\right|=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}2x+8=0\\y+x=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=-8\\y=8\end{matrix}\right.\)

Vậy ..