bt làm r

\(A=131\cdot\left(35-27\right)-35\cdot31+131\cdot207\\ A=131\cdot35+131\cdot27-35\cdot31+131\cdot207\\ A=35\cdot\left(131-31\right)+131\cdot\left(27+207\right)\\ A=35\cdot100+131\cdot234\\ A=3500+30654=34154\)

Thank you very much

a ) 1 101 + 1 102 + 1 103 + ... + 1 149 + 1 150 > 1 150 + 1 150 + ... + 1 150 ⏟ 50 s o = 1 3

b ) 1 201 + 1 202 + ... + 1 400 < 1 200 + 1 200 + ... + 1 200 ⏟ 200 s o = 1

c) đặt S= 1 31 + ... + 1 40 + 1 41 + ... + 1 50 + 1 51 + ... + 1 60

S > 1 40 + .. + 1 40 ⏟ 10 s o + 1 50 + ... + 1 50 ⏟ 10 s o + 1 60 + ... + 1 60 ⏟ 10 s o = 1 40 + 1 50 + 1 60 = 37 60

M à       37 60 > 36 60 = 3 5 = > S > 3 5

S < 1 30 + .. + 1 30 ⏟ 10 s o + 1 40 + ... + 1 40 ⏟ 10 s o + 1 50 + ... + 1 50 ⏟ 10 s o = 10 30 + 10 40 + 10 50 = 47 60

M à       47 60 < 48 60 = 4 5 = > S < 4 5

Bài này mình làm xong rồi nhưng lỡ tay bấm nút hủy.

MONG CÁC BẠN  

\(\frac{-1}{2}-\frac{-3}{5}+\frac{-1}{9}+\frac{1}{131}-\frac{-2}{7}+\frac{4}{35}-\frac{7}{18}\)

\(=\frac{-1}{2}+\frac{3}{5}-\frac{1}{9}+\frac{1}{131}+\frac{2}{7}+\frac{4}{35}-\frac{7}{18}\)

\(=\frac{1}{10}-\frac{122}{1179}+\frac{2}{5}-\frac{7}{18}\)

\(=-\frac{41}{11790}+\frac{1}{90}\)

\(=\frac{1}{131}\)

học tốt

a: 29+131+237+763

=160+1000

=1160

b: 65+327+15+73

=65+15+327+73

=80+400

=480

c: \(12+54:8-8\)

=12+3-8

=15-8

=7

d: \(45\cdot58+45\cdot42\)

\(=45\cdot\left(58+42\right)\)

\(=45\cdot100=4500\)

e: \(35\cdot34+35\cdot26+40\cdot35\)

\(=35\cdot\left(34+26+40\right)\)

\(=35\cdot100=3500\)

f: \(65\cdot25+65\cdot45+30\cdot65\)

\(=65\cdot\left(25+45+30\right)\)

\(=65\cdot100=6500\)

g: \(750:\left\lbrace32-\left\lbrack2^2+\left(5\cdot3^2-42\right)\right\rbrack\right\rbrace+100\)

\(=\frac{750}{32-\left\lbrack4+5\cdot9-42\right\rbrack}+100=\frac{750}{32-4-45+42}+100\)

\(=\frac{750}{28-3}+100\)

=750:25+100

=30+100

=130

h: \(\left\lbrace630:\left\lbrack16+3\cdot\left(6+3\cdot4\right)\right\rbrack\right\rbrace-1\)

\(=\frac{630}{16+3\cdot\left(6+12\right)}-1=\frac{630}{16+3\cdot18}-1\)

\(=\frac{630}{70}-1\)

=9-1=8

i: \(5871:\left\lbrack928-\left(247-82\right)\cdot5\right\rbrack+2175^0\)

\(=\frac{5871}{928-165\cdot5}+1\)

\(=\frac{5871}{928-825}+1=\frac{5871}{103}+1=57+1=58\)

k: \(375:\left\lbrace32-\left\lbrack4+\left(5\cdot3^2-42\right)\right\rbrack\right\rbrace-14\)

\(=\frac{375}{32-\left\lbrack4+5\cdot9-42\right\rbrack}-14\)

\(=\frac{375}{32-\left\lbrack4+45-42\right\rbrack}-14=\frac{375}{32-\left(4+3\right)}-14=\frac{375}{32-7}-14\)

\(=\frac{375}{25}-14\)

=15-14

=1