\(6⋮\left(x-1\right)\)

\(\Rightarrow x-1\in\text{ư}\left(6\right)=1.2.3.6\)

\(\Rightarrow x-1=1\)

\(\Rightarrow x-1=2\)

\(\Rightarrow x-1=3\)

\(\Rightarrow x-1=6\)

\(x=1+1=2\)

\(x=1+2=3\)

\(x=1+3=4\)

\(x=1+6=7\)

=> x - 1 \(\in U\left[6\right]\in\left\{-6;-3;-2;-1;1;2;3;6\right\}\)

\(\Rightarrow x\in\left\{-5;-2;-1;0;2;3;4;7\right\}\)

x - 1 thuộc Ư { 6 } = { -6 ; -3 ; -2 ; -1 ; 1 ; 2 ; 3 ; 6 }

Suy ra x thuộc { -5 ; -2 ; -1 ; 0 ; 1 ; 2 ; 3 ; 4 ; 7 }

Khỏi cần ngoặc nha Songoku Sky Fc11

2002 - 57 - 2002

= 2002 - 2002 - 57 = -57

k cho bạn Trần Nhật Quỳnh nha bạn ấy làm đúng rồi

2002 - 57 - 2002

= 2002 - 2002 - 57

= 0 - 57

= -57

\(\left(2002\right)-\left(57-2002\right)\)

\(=2002-2002-57\)

\(=\)\(0-57\)

\(=-57\)

=(-7) nhé bạn!

mình nha!

nhiều quá

A = 1+5+5²+5³+....+5⁵⁰

5A = 5+5²+5³+5⁴+...+5⁵¹

4A = 5A - A = 5⁵¹ - 1

=> A = \(\frac{5^{51}-1}{4}\)

Ta có: A=1+5+5²+5³+…+5⁴⁹+5⁵⁰

=>5.A=5+5²+5³+5⁴+…+5⁵⁰+5⁵¹

=>5.A-A=5+5²+5³+5⁴+…+5⁵⁰+5⁵¹-1-5-5²-5³-…-5⁴⁹-5⁵⁰

=>4.A=5⁵¹-1

=>\(A=\frac{5^{51}-1}{4}\)

    không ghi lại đề nha !!! 

=  0,13 x 100 x 12,5 -  6,5 x 2 x 2,5 

=        13        x 12,5 -     13    x 2,5 

=              13 x ( 12,5 - 2,5 )

=                 13    x   10

=                        130 

?????????????????????????????????????????????????

0,13:0.01x12,5 - 6,5:0,5x2,5

=0,13x100x12,5 - 6,5x2x2,5

=13x12,5 - 13x2,5

=13x( 12,5-2,5)

=13x10

=130

\(\frac{1}{x}+\frac{1}{y}+\frac{1}{z}=0\)

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

\(P=\frac{y+z}{x}+\frac{z+x}{y}+\frac{x+y}{z}\)

\(=\frac{y}{x}+\frac{z}{x}+\frac{z}{y}+\frac{x}{y}+\frac{x}{z}+\frac{y}{z}\)

\(=y\left(\frac{1}{x}+\frac{1}{z}\right)+x\left(\frac{1}{z}+\frac{1}{y}\right)+z\left(\frac{1}{x}+\frac{1}{y}\right)\)

\(=y.\frac{-1}{y}+x.\frac{-1}{x}+z.\frac{-1}{z}\)

\(=-1-1-1=-3\)

P+3=\(\frac{y+z}{x}+1+\frac{x+z}{y}+1+\frac{x+y}{z}+1=\frac{x+y+z}{x}+\frac{x+y+z}{y}+\frac{x+y+z}{x}\)

P+3=\(\left(x+y+z\right)\left(\frac{1}{x}+\frac{1}{y}+\frac{1}{z}\right)=0.\left(x+y+z\right)=0\)

=> P=\(-3\)

Chuc ban hoc tot

Ta có : \(P=\frac{y+z}{x}+\frac{z+x}{y}+\frac{x+y}{z}\)

\(\Rightarrow P+3=\frac{y+z}{x}+1+\frac{z+x}{y}+1+\frac{x+y}{z}+1\)

\(\Rightarrow P+3=\frac{x+y+z}{x}+\frac{x+y+z}{y}+\frac{x+y+z}{z}\)

\(\Rightarrow P+3=\left(x+y+z\right).\frac{1}{x}+\left(x+y+z\right).\frac{1}{y}+\left(x+y+z\right).\frac{1}{z}\)

\(\Rightarrow P+3=\left(x+y+z\right).\left(\frac{1}{x}+\frac{1}{y}+\frac{1}{z}\right)\)

\(\Rightarrow P+3=\left(x+y+z\right).0\)

\(\Rightarrow P+3=0\)

\(\Rightarrow P=-3\)

Vậy P = - 3

Diện tích tấm bìa là :

        0,5 x 0,5 x 6 - 0,5 = 1 ( m²)

                     Đáp số : 1 m²

* 2xy + 1 =n²(1)

   3xy+1=m²(2)

(1) => 2xy chia hết cho 8 => xy chia hết cho 4 

(2)=>3xy chia hết cho 8  mà (3;8)=1 => xy chia hết cho 8 

*(1)+(2)

=> 5xy +2=m²+n²

VP chia 5 dư 2 => m²+n² chia 5 dư 2 => m² và n² chia 5 dư 1 

=>xy chia hết cho 5 

(8;5)=1

=>xy chia hết cho 40