Gọi số công nhân của ba nhóm I, II, III lần lượt là x, y, z (người)
(x, y, z  N* và x, y, z < 39). 0,5
Vì đội công nhân có 39 người  x + y + z = 39. 
Nếu thêm 1 người vào nhóm I, thêm 2 người vào nhóm II và bớt 3 người của nhóm
III thì số công nhân của ba nhóm I, II, III tỉ lệ nghịch với các số 4; 3; 2  4(x + 1)
= 3(y + 2) = 2(z -3)

4 x +1 3 y + 2 2 z -3       x +1 y + 2 z -3 = = = = = 12 12 12 3 4 6 
x +1+ y + 2+ z -3 x + y + z 39 = = = = 3 3+ 4+ 6 13 13 0,25
Tìm được x = 8, y = 10, z = 21 (thỏa mãn x, y, z  N* và x, y, z < 39)
Vậy số công nhân của ba nhóm I, II, III lần lượt là 8, 10, 21 (người)

Theo bài ra khi thêm 1 người vào nhóm I, thêm 2 người vào nhóm II ( tức là thêm 3 người vào cả 2 nhóm ) và bớt 3 người nhóm III thì tổng số người của 3 nhóm là không đổi .

Gọi số người của ba nhóm I,II,III lần lượt là : a,b,c

Ta có :  a.4 = b.3 = c.2 hay a/1/4 = b/1/3 = c/1/2

Theo tính chất dãy tỉ số bằng nhau, ta có :

 a/1/4 = b/1/3 = c/1/2 = a + b + c/1/4 + 1/3 + 1/2 = 39/13/12= 36

=> a = 36 . 1/4 = 9

     b = 36 . 1/3 = 12

     c = 36 . 1/2 = 18

Hok tốt !

\(x,y\inℤ\)phải không?

Ta có:

\(\left(x^2y^2+4x^2+2y^2-4\right)-\left(x^2y^2+5x^2+y^2-3\right)=0\)\(=0\)

\(\Rightarrow x^2y^2+4x^2+2y^2-4-x^2y^2-5x^2-y^2+3=0\) (bỏ ngoặc đổi dấu)

\(\Rightarrow\left(x^2y^2-x^2y^2\right)+\left(4x^2-5x^2\right)+\left(2y^2-y^2\right)+\left(-4+3\right)=0\)

\(\Rightarrow0-x^2+y^2-1=0\)

\(\Rightarrow y^2-x^2=1\)

\(\Rightarrow\left(y-x\right)\left(y+x\right)=1\)

Vậy ta có

\(\left(y-x\right)=1;\left(y+x\right)=1\)\(\Rightarrow y=1;x=0\)

Hoặc \(\left(y-x\right)=-1;\left(y+x\right)=-1\)\(\Rightarrow y=-1;x=0\)

Vậy ...

(Không biết đúng không nữa, nếu thấy đúng thì t***k mik nhé!)

A=2018x-2017x-2016x-x

A=(2018-2017-2016-...-1)x

A=[(2018-2017)-(2017-2016)-....-(2-1)].x

A=(1-1-....-1)x

A=[1-(1+1+...+1)]x

A=(1-1008)x

A=-1007x

Thay x=2017 vào A ta có

A=-1007.2017= -2031119

Vậy A=-2031119

tổng số lần bắn súng là bao nhiêu vậy bạn???

tổng số điểm bắn là

10*25+9*10+8n+7*4+6*5=398+8n

và 8,92(25+10+n+4+5)=392,48+8,92n

như vậy ta có pt:

398+8n=392,48=8,92n

5,52n=0,92

n=6

89 độ nha !

https://olm.vn/hoi-dap/detail/212899860100.html , tham gia có thưởng

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xin lỗi mk ko bt giải vì chưa ok 

ai như vậy thì k mk nha