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\(\frac{\left(120+60\right)}{12}=\frac{120}{12}+\frac{60}{12}=10+5=15\)
\(78\cdot31+78\cdot17+78\cdot24+22\cdot72=78\left(31+17+24\right)+22\cdot72\)
\(=78\cdot72+22\cdot72=72\left(78+22\right)=72\cdot100=7200\)
\(997+86=997+\left(83+3\right)=\left(997+3\right)+83\)
\(=1000+83=1083\)
\(5\cdot25\cdot2\cdot37\cdot4=\left(5\cdot2\right)\cdot\left(25\cdot4\right)\cdot37\)
\(=10\cdot100\cdot37=37000\)
\(558+336+442+664=\left(558+442\right)+\left(336+664\right)\)
\(=1000+1000=2000\)
5 x 25 x 2 x 37 x 4
= ( 5 x 2 ) x ( 25 x 4 ) x 37
= 10 x 100 x 37
= 1000 x 37
= 37000
Tính nhanh
Ạ) ( 12 x 2 + 12 x 4 - 12 x 6) : ( 2 + 4 + 6 +... + 12 + 14)
b) 37 x 49 + 37 x 2 x 25 + 37
A) (12 x 2 + 12 x 4 + 12 x 6) : ( 2 + 4 + 6 + ... + 12 + 14)
= [12 x ( 2 + 4 - 6 )] : ( 2 + 4 + 6 + ... + 12 + 14)
= [12 x 0 ] : ( 2 + 4 + 6 + ... + 12 + 14)
= 0 : ( 2 + 4 + 6 + ... + 12 + 14)
= 0
B) 37 x 49 + 37 x 2 x 25 + 37
= 37 x (49 + 2 x 25 + 1)
= 37 x 100
= 3700
Học dỏi nha :)))
~ Good luck ~
3 × 25 × 8 + 4 × 37 × 6 + 2 × 38 × 12
= ( 3 × 8 ) × 25 + ( 4 × 6 ) × 37 + ( 2 × 12 ) × 38
= 24 × 25 + 24 × 37 + 24 × 38
= 24 × ( 25 + 37 + 38 )
= 25 × 100
= 2 500
35 × 34 + 35 × 66 + 65 × 55 + 65 × 45
= 35 × ( 34 + 66 ) + 65 × ( 55 + 45 )
= 35 × 100 + 65 × 100
= 100 × ( 35 + 65 )
= 100 × 100
= 10 000
Cách 1 :
136 × 68 + 16 × 272
= 136 × 2 × 34 + 16 × 272
= 272 × 34 + 16 × 272
= 272 × ( 34 + 16 )
= 272 × 50
= 13 600
Cách 2 :
136 × 68 + 16 × 272
= 136 × 68 + 16 × 2 × 136
= 136 × 68 + 32 × 136
= 136 × ( 68 + 32 )
= 136 × 100
= 13 600
a) \(3.25.8+4.37.6+2.38.12=24.25+24.37+24.38\)
\(=24.\left(25+37+38\right)=24.100=2400\)
b) \(35.34+35.66+65.55+65.45\)
\(=35.\left(34+66\right)+65.\left(55+45\right)=35.100+65.100\)
\(=100.\left(35+65\right)=100.100=10000\)
c) \(136.68+16.272=136.68+32.136\)
\(=136.\left(68+32\right)=136.100=13600\)
p/s: dấu "." là dấu nhân
37 x 23,6 + 55 x 82,6 + 31,4 x 37 - 19,6 x 55=156084887,2 nha bn!
\(\dfrac{7}{2}+\dfrac{19}{6}+\dfrac{37}{12}+...+\dfrac{397}{132}\\ =\left(3+\dfrac{1}{2}\right)+\left(3+\dfrac{1}{6}\right)+\left(3+\dfrac{1}{12}\right)+...+\left(3+\dfrac{1}{132}\right)\)
\(=\left(3+3+3+...+3\right)+\left(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+...+\dfrac{1}{132}\right)\)
\(=\left(3+3+3+...+3\right)+\left(\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+...+\dfrac{1}{11\times12}\right)\)
\(=3\times11+\left(\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{11}-\dfrac{1}{12}\right)\)
\(=33+1-\dfrac{1}{12}=\dfrac{407}{12}\)
a) 35 x 12 + 65 x 13
= 35 x 12 + 65 x (12+1)
=35 x 12 + 65 x 21 + 65
=12 x (65 + 35) + 65
= 12 x 100 + 65
= 1200 + 65
= 1265
b) (37 x 13 -13) : (24 + 37 x 12)
= [ 37 x (12+1) - 13 ] : (24 + 37 x 12)
=( 37 x 12 + 37 - 13) : ( 24 +37 x 12)
=( 37 x 12 +24) : (24 + 37 x 12)
=\(1\)
Ta có nhận xét phần b hai tích chia cho nhau mà 2 tích giống nhau vậy kết quả là \(1\)
35 x 12 + 65 x 13 = 1265
( 37 x 13 - 13) : (24 + 37 x 12) = 1
\(12\times78+12\times22\)
\(=12\times\left(78+22\right)\)
\(=12\times100\)
\(=1200\)
\(---------------\)
\(37\times55+37\times25+37\times20\)
\(=37\times\left(55+25+20\right)\)
\(=37\times100\)
\(=3700\)
a)
12 x 78 + 12 x 22
= 12 ( 78 + 22 )
= 12 x 100
= 1200
b)
37 x 55 + 37 x 25 + 37 x 20
= 37 ( 55 + 25 + 20 )
= 37 x 100
= 3700