Sắp xếp như đề bài là đúg!

Lời giải:

$A=\frac{2^{10}+2-1}{2^9+1}=\frac{2(2^9+1)-1}{2^9+1}=2-\frac{1}{2^9+1}$

$B=\frac{2^{12}+1}{2^{11}+1}=\frac{2(2^{11}+1)-1}{2^{11}+1}=2-\frac{1}{2^{11}+1}$

Vì $2^9+1< 2^{11}+1\Rightarrow \frac{1}{2^9+1}> \frac{1}{2^{11}+1}$

$\Rightarrow 2-\frac{1}{2^9+1}< 2-\frac{1}{2^{11}+1}$

$\Rightarrow A< B$

6: =x^2-7xy+5xy-35y^2

=x(x-7y)+5y(x-7y)

=(x-7y)(x+5y)

7: =x^2-2xy-8xy+16y^2

=x(x-2y)-8y(x-2y)

=(x-2y)(x-8y)

8: =3x^2-6xy-4xy+8y^2

=3x(x-2y)-4y(x-2y)

=(x-2y)(3x-4y)

9: =4x^2+4xy+y^2-16y^2

=(2x+y)^2-16y^2

=(2x+y-4y)(2x+y+4y)

=(2x-3y)*(2x+5y)

10: =2(x^2+5xy+4y^2)

=2(x+y)(x+4y)

11: =5x(x+2y+y^2)

x = -213 nha bạn 

ta có 

           \(\frac{x+1}{212}+\frac{x+2}{211}+\frac{x+3}{210}+\frac{x+4}{209}=-4\)\(-4\)

\(\Rightarrow\left(\frac{x+1}{212}+1\right)+\left(\frac{x+2}{211}+1\right)+\left(\frac{x+3}{210}+1\right)+\left(\frac{x+4}{209}+1\right)=-4+4\)

 =>   \(\frac{x+1+212}{212}+\frac{x+2+211}{211}+\frac{x+3+210}{210}+\frac{x+4+209}{209}\) =\(0\)

=>     \(\frac{x+213}{212}+\frac{x+213}{211}+\frac{x+213}{210}+\frac{x+213}{209}\)=\(0\)

=>      (x+213) \(\left(\frac{1}{212}+\frac{1}{211}+\frac{1}{210}+\frac{1}{209}\right)\)=0

mà\(\left(\frac{1}{212}+\frac{1}{211}+\frac{1}{210}+\frac{1}{209}\right)\)\(\ne0\)

=>x+213=0   => x=-213

vậy x= -213

\(\frac{x+1}{212}+\frac{x+2}{211}+\frac{x+3}{210}+\frac{x+4}{209}=-4\)

\(\Rightarrow\frac{x+1}{212}+1+\frac{x+2}{211}+1+\frac{x+3}{210}+1+\frac{x+4}{209}+1=-4+4=0\)

\(\Rightarrow\frac{x+213}{212}+\frac{x+213}{211}+\frac{x+213}{210}+\frac{x+213}{209}=0\)

\(\Rightarrow\left(x+213\right)\left(\frac{1}{212}+\frac{1}{211}+\frac{1}{210}+\frac{1}{209}\right)=0\)

\(\Rightarrow x+213=0\Leftrightarrow x=-213\)

765-211-212=342

765 - 211 - 212

= 554 - 212

=    342

765-211-212

=554-212

=342

7+6=113

6 + 4 = 210

9 + 8 = 117

3 + 2 = 15 

7 + 5 = 212

7 + 6 = 13

Toán đố mẹo chớ j! làm sao thì làm chớ 7 + 6 = 13 rùi! =)))

ai trả lời là 7+6=13 là sai

7+4=11

6+4=210

7+5=212

9+4=513

7+6=113

5+2=37

7+4=???

trl

7 + 4= 311

6 + 4 = 210

7 + 5 = 212 

9 + 4 = 513

7+ 6 = 113

5 + 2 = 37

7 + 4 = 311 nha các bạn.        cách tính : 7 - 4 = 3 viết 3     7 + 4 = 11   viết 11 thành ra là 311

k cho mik với nhé