tính nhanh
a, 136 x 68 + 16 x 212
b, 43 x (85 - 81) + 85 x (81 - 430
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a) \(\dfrac{25}{37}\times\dfrac{18}{29}+\dfrac{18}{29}\times\dfrac{12}{37}\)
\(=\dfrac{18}{29}\times\left(\dfrac{25}{37}+\dfrac{12}{37}\right)\)
\(=\dfrac{18}{29}\times\dfrac{37}{37}\)
\(=\dfrac{18}{29}\times1\)
\(=\dfrac{18}{29}\)
b) \(\dfrac{31}{85}\times\dfrac{11}{19}+\dfrac{31}{85}\times\dfrac{12}{19}-\dfrac{42}{19}\times\dfrac{31}{85}\)
\(=\dfrac{31}{85}\times\left(\dfrac{11}{19}+\dfrac{12}{19}-\dfrac{42}{19}\right)\)
\(=\dfrac{31}{85}\times\dfrac{-19}{19}\)
\(=\dfrac{31}{85}\times-1\)
\(=-\dfrac{31}{85}\)
c) \(\dfrac{16}{53}:\dfrac{17}{9}-\dfrac{16}{53}:\dfrac{17}{8}\)
\(=\dfrac{16}{53}:\left(\dfrac{9}{17}-\dfrac{8}{17}\right)\)
\(=\dfrac{16}{53}:\dfrac{1}{17}\)
\(=\dfrac{16}{901}\)
c) \(\dfrac{1}{5}\times\dfrac{12}{31}\times\dfrac{4}{3}+\dfrac{19}{31}\times\dfrac{4}{15}\)
\(=\dfrac{4}{15}\times\dfrac{12}{31}+\dfrac{19}{31}\times\dfrac{4}{15}\)
\(=\dfrac{4}{15}\times\left(\dfrac{12}{31}+\dfrac{19}{31}\right)\)
\(=\dfrac{4}{15}\times\dfrac{31}{31}\)
\(=\dfrac{4}{15}\times1\)
\(=\dfrac{4}{15}\)
a: =18/29*(25/37+12/37)
=18/29
b: =31/85(11/19+12/19-42/19)
=-31/85
c; =16/53(9/17+8/17)=16/53
d: =4/15(12/31+19/31)=4/15
43x (85-81) + 85x(81-43)
= 43 x 85 - 43 x 81 + 85 x 81 - 85x 43
= 43 x 85 - 85 x 43 + 85x 81 - 43x 81
= 0 + 81 x ( 85 - 43 )
= 0 + 3402
= 3402
2014 x (128 x 68 - 64 x 136) + 2015
2014 x (8704 - 8704) + 2015
2014 x 0 + 2015
0 + 2015
= 2015
A = 2015
a ) x : − 7 – 6 = − 15 x : − 7 = − 9 x = − 9 . − 7 x = 63
b ) x : 12 – 12 = − 37 x : 12 = − 25 x = − 25 . 12 x = 3 00
c ) x : − 25 + 81 = 85 x : − 25 = 4 x = 4 . − 25 x = − 1 00
Nguyễn Hoàng Thiên Di
tính thường cx đc mà tính nhanh càng tốt nha
a: \(32684+41325+316+675\)
\(=\left(32684+316\right)+\left(41325+675\right)\)
\(=33000+42000=75000\)
b: \(25\cdot18\cdot4\cdot2\)
\(=18\cdot2\cdot\left(25\cdot4\right)\)
\(=36\cdot100=3600\)
c: \(19\cdot81+19+18\cdot19\)
\(=19\left(81+1+18\right)\)
\(=19\cdot100=1900\)
A, 32684 + 41325 + 316 + 675
=(32684+316)+(41325+675)
=33000+42000
=75000
B, 25 x 18 x 4 x 2
=(25x4)x(18x2)
=100x36
=3600
C, 19 x 81 + 19 + 18 x 19
=19x(81+18+1)
=19x100
=1900
a , 12640
b , - 29493
a) = 136 + 16 * ( 68 + 212 )
= 152 * 280
= 42560
b) = 43 * 85 - 81 + 85 * 81 - 430
= ( 85 - 85 ) + (81 - 81) * 430 + 43
= 0 + 0 * 473
= 0
nhớ k nha