2, 

a) \(315-\left(135-x\right)=215\)

\(\Rightarrow135-x=315-215\)

\(\Rightarrow135-x=100\)

\(\Rightarrow x=135-100\)

\(\Rightarrow x=35\)

b) \(x-320:32=25\cdot16\)

\(\Rightarrow x-10=5^2\cdot4^2\)

\(\Rightarrow x-10=20^2\)

\(\Rightarrow x-10=400\)

\(\Rightarrow x=410\)

c) \(3\cdot x-2018:2=23\)

\(=3\cdot x-1009=23\)

\(\Rightarrow3\cdot x=1032\)

\(\Rightarrow x=1032:3\)

\(\Rightarrow x=344\)

d) \(280-9\cdot x-x=80\)

\(\Rightarrow280-x\cdot\left(9+1\right)=80\)

\(\Rightarrow280-10\cdot x=80\)

\(\Rightarrow10\cdot x=280-80\)

\(\Rightarrow10\cdot x=200\)

\(\Rightarrow x=20\)

e) \(38\cdot x-12\cdot x-x\cdot16=40\)

\(\Rightarrow x\cdot\left(38-12-16\right)=40\)

\(\Rightarrow x\cdot10=40\)

\(\Rightarrow x=40:10\)

\(\Rightarrow x=4\)

bài 1 cậu ko giải giúp mình dc à

mik ko hieu lam

2:

a: \(2^2\cdot3-4=4\cdot3-4=12-4=8\)

b: \(16-2^3\cdot2=16-2^4=16-16=0\)

c: \(4^2-4\cdot2=16-8=8\)

d: \(3^3-2\cdot3^2=27-2\cdot9=27-18=9\)

e: \(7^2-9\cdot2^2=49-9\cdot4=49-36=13\)

f: \(2^2\cdot3+4^2=4\cdot3+16=12+16=28\)

Bài 1:

a: \(13+21\cdot5-\left(198:11-8\right)\)

\(=13+105-18+8\)

=21+87

=108

b: \(272:16-5+4\cdot\left(30-5-255:17\right)\)

\(=17-5+4\cdot\left(30-5-15\right)\)

\(=12+4\cdot10=12+40=52\)

c: \(15\cdot24-14\cdot5\cdot\left(145:5-27\right)\)

\(=360-70\left(29-27\right)\)

=360-140

=220

d: \(18\cdot3-18\cdot2+3\cdot\left(\dfrac{51}{17}\right)\)

\(=18\left(3-2\right)+3\cdot3\)

=18+9

=27

e: \(64+115+36-25\cdot8\cdot6\cdot2^2\cdot3+4^2\)

\(=100+115-200\cdot6\cdot4\cdot3+16\)

\(=231-14400=-14169\)

f: \(15\cdot8-\left(17-30+83\right)-144:6\)

\(=120-24-\left(100-30\right)\)

=96-70

=26

a) \(\frac{5}{6}-\left|1-x\right|=\frac{1}{2}\)

<=> \(\left|1-x\right|=\frac{5}{6}-\frac{1}{2}\)

<=>\(\left|1-x\right|=\frac{1}{3}\)

<=>\(\orbr{\begin{cases}1-x=\frac{1}{3}\\1-x=-\frac{1}{3}\end{cases}}\)

<=>\(\orbr{\begin{cases}x=1-\frac{1}{3}\\x=1-\left(-\frac{1}{3}\right)\end{cases}}\)

<=>\(\orbr{\begin{cases}x=\frac{2}{3}\\x=\frac{4}{3}\end{cases}}\)

Vậy \(x=\frac{2}{3}\)hoặc\(x=\frac{4}{3}\)

b) \(\frac{8^5.\left(-5\right)^8+\left(-2\right)^5.\left(-10\right)^9}{4^{10}.5^7+20^8.4}.\frac{144}{25}\)

\(=\frac{2^{15}.5^8+2^5.2^9.5^9}{2^{20}.5^7+2^{16}.5^8.2^2}.\frac{2^4.3^2}{5^2}\)

\(=\frac{2^{14}.5^8.\left(2+5\right)}{2^{18}.5^7.\left(2^2+5\right)}.\frac{2^4.3^2}{5^2}\)

\(=\frac{2^{14}.5^8.7}{2^{18}.5^7.3^2}.\frac{2^4.3^2}{5^2}\)

\(=\frac{2^{18}.3^2.5^8.7}{2^{18}.3^2.5^9}\)

\(=\frac{7}{5}\)

Học tốt!!!!

a.\(\frac{5}{6}-\left|1-x\right|=\frac{1}{2}\)

\(=>\left|1-x\right|=\frac{5}{6}-\frac{1}{2}\)

\(=>\left|1-x\right|=\frac{1}{3}\)

\(=>\orbr{\begin{cases}1-x=\frac{1}{3}\\1-x=\frac{-1}{3}\end{cases}}\)

\(=>\orbr{\begin{cases}x=1-\frac{1}{3}=\frac{2}{3}\\x=1-\frac{-1}{3}=\frac{4}{3}\end{cases}}\)

a)210-475-100+670

=(-365)+670

=305

b)114-(-6)+7-20

=114+6+7-20

=120+7-20

=120-20+7

=100+7

=107

c)215+[144-(144+215)]

=215+[144-144-215]

=215+[0-215]

=215+(-215)

=0

d) (-20).17-45.83

=(-340)-3735

=(-4075)

a) x = 34             

b) x= 5                

c) x = 35              

d) x = 0

e) x = 410            

f) x= 170

A.( 13 + 25 ) + ( 24 - 13 - 42 - 25 )

= 13 + 25 + 24 - 13 - 42 - 25

= ( 13 - 13 ) + ( 25 - 25 ) + ( 24 - 42 )

= 0 + 0 + ( - 18 )

= -18

B. ( 215 - 34 + 127 ) - ( 315 - 144 - 227 )

= 215 - 34 + 127 - 315 + 144 + 227

= ( 215 - 315 ) + ( 144 - 34 ) + ( 127 + 227 )

= - 100 + 110 + 354

= 10 + 354

= 364

Bài 1:

a) Ta có: \(\frac{8}{40}+\frac{-4}{20}-\frac{3}{5}\)

\(=\frac{1}{5}+\frac{-1}{5}-\frac{3}{5}\)

\(=\frac{-3}{5}\)

b) Ta có: \(\frac{-7}{12}+\frac{-2}{12}-\frac{-3}{36}\)

\(=\frac{-7}{12}+\frac{-2}{12}-\frac{-1}{12}\)

\(=\frac{-9+1}{12}=\frac{-8}{12}=\frac{-2}{3}\)

c) Ta có: \(\left(\frac{1}{6}+\frac{-4}{13}\right)-\left(-\frac{17}{6}-\frac{30}{13}\right)\)

\(=\frac{1}{6}+\frac{-4}{13}+\frac{17}{6}+\frac{30}{13}\)

\(=3+2=5\)

d) Ta có: \(-\frac{-5}{4}+\frac{7}{4}-\frac{-11}{7}+\frac{2}{7}\)

\(=\frac{5}{4}+\frac{7}{4}+\frac{11}{7}+\frac{2}{7}\)

\(=3+\frac{13}{7}=\frac{21}{7}+\frac{13}{7}=\frac{34}{7}\)

e) Ta có: \(-\frac{1}{8}+\frac{-7}{9}+\frac{-7}{8}+\frac{6}{7}+\frac{2}{14}\)

\(=-1+1+\frac{-7}{9}\)

\(=-\frac{7}{9}\)

f) Ta có: \(\frac{-2}{9}-\frac{11}{-9}+\frac{5}{7}-\frac{-6}{-7}\)

\(=\frac{-2-\left(-11\right)}{9}+\frac{5-6}{7}\)

\(=1+\frac{-1}{7}=\frac{7}{7}+\frac{-1}{7}=\frac{6}{7}\)