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C
27 tháng 5 2022
Tính nhanh:
a, 18,25 - 3,78 + 1,58
= 18,25 - ( 3,78 + 1,58 )
= 18,25 - 5,36
= 12,89
b, 183 x ( 48 + 54 ) - 83 x ( 54 + 48 )
= 183 x 102 - 83 x 102
= 102 x ( 183 - 83 )
= 102 x 100
= 10200
c, 2,4 x 178 x 2 - 3 x 78 x 1,6
= ( 2,4 x 178 x 2 ) - ( 3 x 78 x 1,6 )
= ( 427,2 x 2 ) - ( 3 x 124,8 )
= 854,4 - 374,4
= 480
d, 3,9 x 138 - 7,8 x 19
= ( 3,9 x 138 ) - ( 7,8 x 19 )
= 538,2 - 148,2
= 390.
8 tháng 6 2021
a) 8,8 : 2,5 + 7,6 : 2,5 - 6,4 : 2,5
= (8,8 + 7,6 - 6,4) : 2,5
= 10 : 2,5
= 4
MN
8 tháng 6 2021
\(a.\)
\(8.8:2.5+7.6:2.5-6.4:2.5\)
\(=\left(8.8+7.6-6.4\right):2.5\)
\(=10:2.5\)
\(=4\)
\(b.\)
\(0.25\times1200+125\times1.5\times2-250\times2.6\)
\(=250\times1.2+250\times1.5-250\times2.6\)
\(=250\times\left(1.2+1.5-2.6\right)\)
\(=250\times0.1=25\)
\(c.\)
\(\left(32\times11-3200\times0.1-32\right):\left(81.6\times27.3-17.3\times81.6\right)\)
\(=\left[32\times\left(11-10-1\right)\right]:\left[81.6\times\left(27.3-17.3\right)\right]\)
\(=0\)
NH
3
ND
Nguyễn Đức Trí
VIP
21 tháng 7 2023
\(...=25x4x\left(7x3+3x4x5+2\right)=100x\left(21+120+2\right)=100x143=14300\)
NH
1
NH
21 tháng 7 2023
7 x 12 x25 +3 x 16 x125 +8 x25
=7 x4 x3 x25 +3 x4 x4 x5 x25+4x2x25
=(4 x25) x(7 x3 +3 x4 x5 +2)
= 100 x (21 +60 +2)
= 100 x 83
= 8300
7 tháng 7 2023
Bài 1
a) \(5\times72\times10\times2=\left(5\times2\times10\right)\times72=100\times72=7200\)
b) \(40\times125=5\times\left(8\times125\right)=5\times1000=5000\)
c) \(16\times6\times25=4\times4\times6\times25=\left(4\times6\right)\times\left(4\times25\right)=24\times100=2400\) Bài 2:
a) \(24\times57+43\times24=24\times\left(57+43\right)=24\times100=2400\)
b) \(12\times19+80\times12+12=12\times\left(19+80+1\right)=12\times100=1200\)
c) \(\left(36\times15\times169\right)\div\left(5\times18\times13\right)\)
\(=\left(18\times2\times3\times5\times13\times13\right)\div\left(5\times18\times13\right)\)
\(=\left(2\times3\times13\right)\times\left(18\times5\times13\right)\div\left(5\times18\times13\right)\)
\(=2\times3\times13\)
\(=78\)
d) \(\left(44\times52\times60\right)\div\left(11\times13\times15\right)\)
\(=\left(4\times11\times4\times13\times4\times15\right)\div\left(11\times13\times15\right)\)
\(=\left(4\times4\times4\right)\times\left(11\times13\times15\right)\div\left(11\times13\times15\right)\)
\(=4\times4\times4\)
\(=64\)
Bài 3:
a) \(x-280\div35=5\times54\)
\(x-8=270\)
\(x=270+8\)
\(x=278\)
b) \(\left(x-280\right)\div35=54\div4\)
\(\left(x-280\right)\div35=\dfrac{27}{2}\)
\(x-280=\dfrac{27}{2}\times35\)
\(x-280=\dfrac{945}{2}\)
\(x=\dfrac{945}{2}+280\)
\(x=\dfrac{1505}{2}\)
c) \(\left(x-128+20\right)\div192=0\)
\(x-128+20=0\times192\)
\(x-128+20=0\)
\(x-128=0-20\)
\(x-128=-20\)
\(x=-20+128\)
\(x=108\)
d) \(4\times\left(x+200\right)=460+85\times4\)
\(4\times\left(x+200\right)=460+340\)
\(4\times\left(x+200\right)=800\)
\(x+200=800\div4\)
\(x+200=200\)
\(x=200-200\)
\(x=0\)
Bài 4:
a) \(\dfrac{7}{12}-\dfrac{5}{12}=\dfrac{2}{12}=\dfrac{1}{6}\)
b) \(\dfrac{8}{11}+\dfrac{19}{11}=\dfrac{27}{11}\)
c) \(\dfrac{3}{8}+\dfrac{5}{12}=\dfrac{9}{24}+\dfrac{10}{24}=\dfrac{19}{24}\)
d) \(\dfrac{3}{4}+\dfrac{7}{12}=\dfrac{9}{12}+\dfrac{7}{12}=\dfrac{16}{12}=\dfrac{4}{3}\)
Bài 5:
a) \(x-\dfrac{6}{7}=\dfrac{5}{2}\)
\(x=\dfrac{5}{2}+\dfrac{6}{7}\)
\(x=\dfrac{47}{14}\)
b) \(\dfrac{12}{7}\div x+\dfrac{2}{3}=\dfrac{7}{5}\)
\(\dfrac{12}{7}\div x=\dfrac{7}{5}-\dfrac{2}{3}\)
\(\dfrac{12}{7}\div x=\dfrac{11}{15}\)
\(x=\dfrac{12}{7}\div\dfrac{11}{15}\)
\(x=\dfrac{180}{77}\)
29 tháng 1
\(A=\left(1-\dfrac{1}{4}\right)\left(1-\dfrac{1}{9}\right)\cdot...\cdot\left(1-\dfrac{1}{9801}\right)\)
\(=\left(1-\dfrac{1}{2}\right)\left(1+\dfrac{1}{2}\right)\left(1-\dfrac{1}{3}\right)\left(1+\dfrac{1}{3}\right)\cdot...\left(1-\dfrac{1}{99}\right)\left(1+\dfrac{1}{99}\right)\)
\(=\left(\dfrac{1}{2}\cdot\dfrac{2}{3}\cdot...\cdot\dfrac{98}{99}\right)\cdot\left(\dfrac{3}{2}\cdot\dfrac{4}{3}\cdot...\cdot\dfrac{100}{99}\right)\)
\(=\dfrac{1}{99}\cdot\dfrac{100}{2}=\dfrac{50}{99}\)
K4
0
T
5
12 tháng 6 2017
a)364+225+436=(364+436)+225=800+225=1025
b)125x14x25x8x4=(125x8)x(25x4)x14=1000x100x14=100000x14=1400000
câu c bạn ra đề sai rồi để mk sửa lại rồi làm luôn.
sửa c) 36x49+64x49=(36+64)x49=100x49=4900
tk nha
12 tháng 6 2017
\(364+225+436\)
\(=\left(364+436\right)+225\)
\(=800+225\)
\(=1025\)
a)49.25.88
=1225.88
=107800
b)12.125.54
=1500.54
=81000
a.107800
b.81000