a) 187 - {[497 - ( 8 x X + 11) : X] : 3 - 78} = 150

=> {[497 - ( 8 x X + 11) : X] : 3 - 78} = 187 - 150

=> {[497 - (8 x X + 11) : X] : 3 - 78} = 37

=> [497 - (8 x X +11): X ] : 3 - 78 = 37

=> [497 - (8 x X + 11) : X] : 3 = 115

=> 497 - ( 8 x X + 11) : X = 345

=> (8 x X  + 11) : X = 497 - 345 = 152

=> 8X + 11 = 152X

=> 152X - 8X = 11

=> 144X = 11

=> X = 11/144

b) 19,96 + 4,19 - 24,15 : \(\left(x:\frac{1}{4}-\frac{1}{4}\right)=23,15\)

=> 19,96 + 4,19 - 24,15 : \(\left(x\cdot4-\frac{1}{4}\right)=23,15\)

=> 24,15 - 24,15 : \(\left(x\cdot4-\frac{1}{4}\right)\)= 23,15

=> 24,15 : \(\left(x\cdot4-\frac{1}{4}\right)\)= 1

=> \(x\cdot4-\frac{1}{4}=24,15\)

=> \(x\cdot4=24,15+\frac{1}{4}=24,4\)

=> x = 24,4 : 4 = 6,1

Còn câu c tương tự

1. \(\left(\frac{2}{11.13}+\frac{2}{13.15}+\frac{2}{15.17}+\frac{2}{17.19}+\frac{2}{19.21}\right)\times462-x=19\)

\(\left(\frac{13-11}{11.13}+\frac{15-13}{13.15}+\frac{17-15}{15.17}+\frac{19-17}{17.19}+\frac{21-19}{19.21}\right)\times462-x=19\)

\(\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+\frac{1}{15}-\frac{1}{17}+\frac{1}{17}-\frac{1}{19}+\frac{1}{19}-\frac{1}{21}\right)\times462-x=19\)

\(\left(\frac{1}{11}-\frac{1}{21}\right)\times462-x=19\)

\(\frac{10}{231}\times462-x=19\)

\(20-x=19\)

\(x=20-19\)

\(x=1\)

2.b \(187-[[497-(8\times x+11)\div x]\div3-78]=150\)

​​\(187-[[497-(\frac{8\times x}{x}+\frac{11}{x})]:3-78]=150\)

\(187-[(497-8-\frac{11}{x}):3-78]=150\)

\(187-[(489-\frac{11}{x}):3-78]=150\)

\(187-[\frac{489}{3}-\frac{33}{x}-78]=150\)

\(187-[163-\frac{33}{x}-78]=150\)

\(187-85+\frac{33}{x}=150\)

\(102+\frac{33}{x}=150\)

\(\frac{33}{x}=150-102\)

\(\frac{33}{x}=48\)

\(x=\frac{48}{33}=\frac{16}{11}\)

k fai tính nhanh thì dùng máy tính nah

1) 18+14+16+35+110+160+150+145+158+140+55+25

= (14+16)+(35+25)+(145+55)+(140+160)+(158+18)+(110+150)

= 30+ 60 +200+ 300+ 176+ 260

= 590+ 436= 1026.

2) 62+ 78 +48+ 96+85+ 91

= (62 +48)+ (96 +85 +91+ 78)

= 110 + 350= 460.

3) 107 +439 + 666 +673+ 358 + 187

= (107 + 673) + ( 439 + 666) + ( 358+ 187)

= 780 + (1105 + 545)

= 780+ 1650= 2430.

4) 187 + 62+ 78+48+ 96+ 85+ 91+107+ 439+ 666+ 673+ 358

= (187 + 673) + ( 62+ 78)+ (439+ 91)+ ( 85+ 358+ 107)+ (666+ 96+ 48) 

= (860+ 140)+ (530+ 550+ 810)

= 1000+ 1890= 2890.

ghê rồi

b,x-1+2x-4+3x-9=22

6x-14=22

6x=36

x=6

a,12x-180+10x-20+39x-2340+65x-4420=780

126x-6960=780

126x=7740

x=430/7

1)

187 + x = 562

          x = 562 - 187

          x = 375

2)

365 - x = 79

         x = 365 - 79

         x = 286

3)

1170 : x = 78

          x = 1170 : 78

          x = 15

4)

x : 852 = 43

x          = 43 x 852

x          = 36 636

1. x = 375

2. x = 286

3. x = 15

4. x = 36636

Ai k mình mình k lại!

1. 375 2. 286 3.15 4. 36636. K mk nha ahihi chúc bạn nám mới dzui dzẻ nhoa !!!!

213 + (X - 25) = -187

=> x - 25 = -187 - 213

=> x = -187 - 213 + 25

=> x = -375

2.(x - 2) + 17 = -13

=> 2.(x - 2) = -13 - 17

=> 2.(X - 2) = -30

=> x - 2 = -30:2

=> x - 2 = -15

=> x = -15 + 2

=> x = -13

x - 8 - 13 = -8

=> x - 21 = -8

=> x = -8 + 21

=> x = 13

x + 11 + 14 = 15

=> x + 25 = 15

=> x = 15 - 25

=> x = -10

a) x- 25= -187 - 213 = -400

   x= -400:25 = -16

b) 2.(x-2) = -13- 17 = -30

       x- 2 = -30 :2 = -15

       x= -15+2 = -13

c) x-8 = -8+13 = 5

   x= 5+8 = 13

d) x+11 = 15-14 = 1

 x= 1-11 = -10

mình thấy cứ kì kì sao ớ