a,

=85.35-85.27-35.85+35.27

=85.35+85.(-27)-35.85+35.27

=85[35+(-27)+(-35)]+35.27

=85.(-27)+35.27

=-85.27+35.27

=27.[(-85)+35]

=27.(-50)

=-1350

các câu còn lại cũng vậy

a, 85 x ( 35- 27 ) - 35 x ( 35 - 27 )

85 x 8 - 35 x 8

8 x ( 85 - 35 ) 

8 x 50 = 400

b, ( -45 ) x 69 + 30 x ( -45 ) +( -45)

( -45 ) x ( 69 + 30 + 1)

-45 x 100 = -4500

c , 26 + 7 x ( 4 - 12 )

26 + 7 x ( - 8 )

26 + ( -56 )=(- 30)

d , 127 - 18 x ( 5 + 6 )

127 - 18 x 11

127 - 180 + 18

-53 + 18 = - 35

a.85x(35-27)-35x(85-27)

=85x8-35x58

=680-2030

=(-1350)

b.(-45)x69+30x(-45)+(-45)

=(-3105)+(-1350)+(-45)

=1800+(-45)

=1755

c.26+7x(4-12)

=26+7x(-8)

=26+(-56)

=(-30)

d.127-18x(5+6)

=127-18x11

=127-198

=(-71)

li-ke cho mình nha bạn

= 27 x 45 + 27 x 55

= 27 x (45 + 55)

= 27 x 100

= 2700

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

\(23+27+1=50+1=51\\ 45+45+25=90+25=115\\ 8+12+3=20+3=23\\ 69+11+4=80+4=84\)

\(\frac{48x700-24x45x20}{45-40+35-30+25-20+15-10}\)

\(=\frac{24x2x700-24x45x20}{5+5+5+5}\)

\(=\frac{24x1400-24x900}{20}\)

\(=\frac{24x\left(1400-900\right)}{20}\)

\(=\frac{24x500}{20}\)

\(=\frac{12000}{20}\)

\(=600\)

k nha

 

\(\frac{27x45+27x55}{2+4+6+...+16+18}\)

\(=\frac{27x\left(45+55\right)}{2+4+6+...+16+18}\)

\(=\frac{27x100}{2+4+6+...+16+18}\)

\(=\frac{2700}{\left(2+18\right)x9:2}\)

\(=\frac{2700}{90}\)

\(=30\)

k nha

 

\(\frac{26x108-26x12}{32-28+24-20+16-12+8-4}\)

\(=\frac{26x\left(108-12\right)}{4+4+4+4}\)

\(=\frac{26x96}{16}\)

\(=\frac{2496}{16}\)

\(=156\)

k nha

A

A

A

-73

Bài 6: Thực hiện phép tính

a)(-18)-(-3)-12

= (-18) + 3 - 12

= (-15) - 12

= - 3

b)85.(35-27)-35.(85-27)

= 85. 8 - 35. 58

= 680. 2030

= 1380400

c)(-45).69+31.(-45)

= (-45) . (69 + 31)

= (-45) . 100

= - 4500

Bài 7:Tìm x thuộc Z, biết:

a)(2-x)+10=-14

2-x = 14 - 10

2-x = 4

x = 2 - 4

x = - 2

b)14.|x|=28

|x| = 28 : 14

|x| = 2

⇒ x ϵ {2;-2}