a, -(-15+125-81)-(-85+75-19+100)

=-15-125+81-(-85)-75+19-100

=-140+81-(-85)-75+19-100

=-59-(-85)-75+19-100

=-16-75+19-100

=-91+19-100

=-72-100

=-172

a: \(5\cdot11\cdot18+9\cdot31\cdot10+4\cdot29\cdot45\)

\(=11\cdot\left(5\cdot18\right)+31\cdot\left(9\cdot10\right)+29\cdot2\cdot\left(2\cdot45\right)\)

\(=90\left(11+31+29\cdot2\right)\)

\(=90\cdot100=9000\)

b: \(37\cdot39+78\cdot14+13\cdot85+52\cdot55\)

\(=37\cdot39+39\cdot2\cdot14+13\cdot85+13\cdot4\cdot55\)

\(=39\left(37+2\cdot14\right)+13\cdot\left(85+4\cdot55\right)\)

\(=39\cdot65+13\cdot305\)

\(=13\left(65\cdot3+305\right)=13\cdot500=6500\)

a)

5.11.18+9.31.10+4.29.455.11.18+9.31.10+4.29.45

=90.11+90.31+2.29.90=90.11+90.31+2.29.90

=90.(11+31+2.29)=90.(11+31+2.29)

=90.100=9000

b)

37.39+78.14+13.85+52.5537.39+78.14+13.85+52.55

=37.39+39.2.14+13.5.17+13.4.5.11=37.39+39.2.14+13.5.17+13.4.5.11

=39.(37+2.14)+65.17+65.44=39.(37+2.14)+65.17+65.44

=39.65+65.(17+44)=39.65+65.(17+44)

=39.65+65.61=39.65+65.61

=65.(39+61)=65.(39+61)

=65.100=6500

a)

5.11.18+9.31.10+4.29.45

=90.11+90.31+2.29.90

=90.(11+31+2.29)

=90.100

=9000

b)

37.39+78.14+13.85+52.55

=37.39+39.2.14+13.5.17+13.4.5.11

=39.(37+2.14)+65.17+65.44

=39.65+65.(17+44)

=39.65+65.61

=65.(39+61)

=65.100

=6500

a) \(39\times118+29\times82\)

\(=39\times2\times59+29\times2\times41\)

\(=2\times\left(39\times59+29\times41\right)\)

\(=2\times\left(2301+1189\right)\)

\(=2\times3490\)

\(=6980\)

b) \(37\times39+78\times14-13\times85-52\times55\)

\(=37\times3\times13+6\times13\times14+13\times85-4\times13\times55\)

\(=13\times\left(37\times3+6\times14+85-4\times55\right)\)

\(=13\times\left(111+84+85-220\right)\)

\(=13\times\left(280-220\right)\)

\(=13\times60\)

\(=780\)

c) \(368:16+752:16+480:16\)

\(=\left(368+752+480\right):16\)

\(=\left(1120+480\right):16\)

\(=1600:16\)

\(=100\)

d) \(5\times11\times18+9\times31\times10+4\times29\times45\)

\(=5\times11\times9\times2+9\times31\times10+2\times2\times29\times5\times9\)

\(=10\times9\times11+10\times9\times31+10\times29\times2\times9\)

\(=90\times11+90\times31+90\times29\times2\)

\(=90\times\left(11+31+29\times2\right)\)

\(=90\times\left(42+58\right)\)

\(=90\times100\)

\(=9000\)

a) \(48.19+48.15+134.52\)

\(=48\left(19+15\right)+6968\)

\(=48.34+6968\)

\(=1632+6968\)

\(=8600.\)

b) \(27.121-87.27+73.34\)

\(=27\left(121-87\right)+73.34\)

\(=27.34+73.34\)

\(=34\left(27+73\right)\)

\(=34.100\)

\(=3400.\)

c) \(125.98-125.46-52-25\)

\(=125\left(98-46\right)-52-25\)

\(=125.52-52-25\)

\(=52\left(125-1\right)-25\)

\(=52.124-25\)

\(=6448-25\)

\(=6423.\)

d) \(136.23+136.17-40.36\)

\(=136\left(23+17\right)-40.36\)

\(=136.40-40.36\)

\(=40\left(136-36\right)\)

\(=40.100\)

\(=4000.\)

e) \(66.25+5.66+66.14+33.94\)

\(=33\left(2.50+5.2+14.2+94\right)\)

\(=33\left(50+10+28+94\right)\)

\(=33.182\)

\(=6006.\)

 2 + 4 + 6 + 8 + ......... + 34 + 36 + 38 + 40
=(2+40)+(4+48)+...+(20+22)
=42*10
=420

 2 + 4 + 6 + 8 + ......... + 34 + 36 + 38 + 40
=(2+40)+(4+48)+...+(20+22)
=42*10
=420

 a) 27 x 39 + 27 x 63 - 2 x 2

= 27 x ( 39 + 63 ) - 2 x 2

= 27 x 102 - 2 x 2

= 2754 - 4

= 2750

b) 48 x 19 + 48 x 115 + 134 x 52

= 48 x ( 19 +115 ) + 134 x 52

= 48 x 134 + 134 x 52

= ( 48 + 52 ) x 134

= 100 x 134

= 13400

chúc các bạn năm mới vui vẻ. bạn tk mk nha.

a) 27 x 39 + 27 x 63 - 2 x 2

= 27 x (39 + 63) - 2 x 2

= 27 x 102 - 2 x 2

= 2754 - 4

= 2750

b) 48 x 19 + 48 x 115 + 134 x 52

= 48 x (19 + 115) + 134 x 52

= 48 x 134 + 134 x 52

= 134 x (48 + 52)

= 134 x 100

= 13400

a,27.39+27.63-2.2

=27.(39+63)-4

=27.102-4

=2754-4

=2750

b,48.19+48.115+134.52

=48.(19+115)+134.52

=48.134+134.52

=134.(48+52)

=134.100

=13400

a) \(85\cdot12,7+5+3+12,7=12,7\left(85+1\right)+8=1092,2+8=1100,2\)

b) \(52\cdot143-52\cdot39-8\cdot28=52\left(143-39\right)-\left(-20\right)=52\cdot104+20=5408+20=5428\)