[50+(55-x)].17=1700

[50+(55-x)]=1700:17

[50+(55-x)]=100

         (55-x)=100-50

             (55-x)=50

                  x=50+55

                 x=105

 720:[31-(2.x-5)]=72

        [31-(2.x-5)]=720:72

        [31-(2.x-5)]=10

              (2.x-5)=31-10

               (2.x-5)=21

               2.x=21+5

               2.x=26

                   x=26:2

                    x=13

\(\left[50+\left(55-x\right)\right].17=1700\)

\(50+55-x=1700:17\)

\(105-x=100\)

\(x=105-100\)

\(x=5\)

vay \(x=5\)

2) \(720:\left[31-\left(2x-5\right)\right]=72\)

\(31-2x+5=720:72\)

\(36-2x=10\)

\(2x=36-10\)

\(2x=26\)

\(x=13\)

vay \(x=13\)

[50+(55-x)] .17 =1700

      50+(55 - x) =1700 :17

       50+(55 - x) =100

       55 - x          =100 - 50  

       55-x            = 50

        x                = 55- 50 

        x                 =5

31^11 và 17^14

31^11 < 32^11 = ( 2⁵ )¹¹= 2^5.11=2⁵⁵

17^14 > 16^ 14 = ( 2⁴)¹⁴=2^4.14=2⁵⁶

Mà 2⁵⁵<2⁵⁶ Nên 31^11<17^14

31^11 và 17^14

31^11 < 32^11 = ( 2⁵ )¹¹= 2^5.11=2⁵⁵

17^14 > 16^ 14 = ( 2⁴)¹⁴=2^4.14=2⁵⁶

Mà 2⁵⁵<2⁵⁶ Nên 31^11<17^14

Thì vì 31¹¹<32¹¹ mà32¹¹=(2⁵)¹¹     thi bằng 2^5×11 =2⁵⁵

Câu kia cũng thế 

Khi 2⁵⁵va2⁵⁶ đã có chung cơ số thì ta so sánh số mũ so mũ nào lớn hơn thì lũy thừa đó lớn hơn 

2⁵⁵<2⁵⁶hay32¹¹<16¹⁴

ta thấy 31¹¹<32¹¹<16¹⁴<17¹⁴

suy ra 31¹¹<17¹⁴

trả lời cho mình nha mình k cho

\(\frac{29}{68}\times\frac{31}{55}+\frac{31}{68}\times\frac{26}{55}=\frac{31}{68}\times\frac{29}{55}+\frac{31}{68}\times\frac{26}{55}\)

                                                    \(=\frac{31}{68}\times\left(\frac{29}{55}+\frac{26}{55}\right)\)

                                                    \(=\frac{31}{68}\)

\(\frac{29}{68}.\frac{31}{55}+\frac{31}{68}.\frac{26}{55}\)

\(=\frac{29}{68}.\frac{31}{55}+\frac{26}{68}.\frac{31}{55}\)

\(=\left(\frac{29}{68}+\frac{26}{68}\right).\frac{31}{55}\)

\(=\frac{55}{68}.\frac{31}{55}\)

\(=\frac{31}{68}\)

Học tốt

Bài 6:

a)\(\left(-18\right)-\left(-3\right)-12\)

\(=\left(-18\right)+3-12\)

\(=-15-12\)

\(=-27\)

b)\(85.\left(35-27\right)-35.\left(85-27\right)\)

\(=85.35-85.27-35.85+35.27\)

\(=85.\left(35-27-35\right)+35.27\)

\(=85.\left(-27\right)+35.27\)

\(=27.\left(-85+35\right)\)

\(=27.\left(-50\right)\)

\(=-1350\)

c)\(\left(-45\right).69+31.\left(-45\right)\)

\(=\left(-45\right).\left(69+31\right)\)

\(=\left(-45\right).100\)

\(=-4500\)

Bài 7:

a)\(\left(2-x\right)+10=-14\)

\(\Rightarrow2-x=-24\)

\(\Rightarrow x=26\)

b)\(14.\left|x\right|=28\)

\(\Rightarrow\left|x\right|=2\)

\(\Rightarrow\orbr{\begin{cases}x=2\\x=-2\end{cases}}\)

c)\(31-\left(17+x\right)=55\)

\(\Rightarrow17+x=-24\)

\(\Rightarrow x=-41\)

(-18)-(-3)-12=-27

85.(35-27)-35.(85-27)=-1350

(-45).69+31.(-45)=-4500

(2-x)+10=-14

\(\Leftrightarrow\)(2-x)=-14-10

\(\Leftrightarrow\)2-x=-24

\(\Rightarrow\)x=2-(-24)

\(\Rightarrow\)x=26

14.lxl=28

\(\Leftrightarrow\)lxl=28:14

\(\Leftrightarrow\)lxl=2

\(\Rightarrow\)x=-2

a. 15.27-3.5.17

=15.27-15.17

=15.(27-17)

=15.10

=150

a, 120
b,10
c,-100
d,0

a) (-125) + 100 + 80 + 125 + 20

= [(-125) + 125] + (80 + 20) + 100

= 0 + 100 + 100

= 200

b) 27 + 55 + (-17) + (-55)

= [27 + (-17)] + [55 + (-55)]

= (27 - 17) + 0

= 10

c) (-92) + (-251) + (-8) + 251

= [(-251) + 251] + [(-92) + (-8)]

= 0 - 100

= -100

d) (-31) + (-95) + 131 + (-5)

= [(-31) + 131) + [(-95) + (-5)]

= 100 + (-100)

= 0 

Hok tốt

a) -125 + 100 + 80 + 125 + 20

= ( -125 + 125 ) + ( 80 + 20 ) + 100

= 0 + 100 + 100

= 200

b) 27 + 55 + (-17) + (-55)

= [ 27 + (-17) ] + [ 55 +(-55) ]

= 10 + 0 

= 10

c) -92 + (-251) + (-8) + 251

= [ -92 + (-8) ] + ( -251 + 251 )

= -100 + 0 

= -100

d) -31 + (-95) + 131 + (-5)

= ( -31 + 131 ) + [ -95 + (-5) ]

= 100 + (-100) = 0