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1a) \(\frac{12}{17}+\frac{19}{17}+\frac{8}{17}\)
\(=\left(\frac{12}{17}+\frac{8}{17}\right)+\frac{19}{17}\)
\(=\frac{20}{17}+\frac{19}{17}\)
\(=\frac{39}{17}\)
b) \(\frac{2}{5}+\frac{7}{12}+\frac{13}{12}\)
\(=\frac{2}{5}+\frac{5}{3}\)
\(=\frac{31}{15}\)
2) \(\frac{25}{3}-x=\frac{5}{6}\)
\(x=\frac{25}{3}-\frac{5}{6}\)
\(x=\frac{45}{6}\)
ủng hộ tớ nha
30x25x7x8
=(30x7)x(25x8)
=210x200
=42000
75x8x12x14
=(75x12)x(8x14)
=900x112
=100800
A) =(30*7)*(25*8)
=210*200
=4200
B)=(75*8)*(12*14)
=600*168
=100800
a) 142 x 12 + 42 x 18
= 142 x (12 +18)
= 142 x 30 = 4260
b) 49 x 365 - 39 x 365
= (49-39) x 365
= 10 x 365 = 3650
c) 4 x 18 x 25
= 18 x (4 x 25)
= 10 x 100 = 1800
a: =100x26=2600
b: =78x10=780
c: =67x100=6700
d: =1000x575=575000
\(4\times26\times25=\left(4\times25\right)\times26=100\times26=2600\\ 63\times78-53\times78=\left(63-53\right)\times78=10\times78=780\\ 67\times92+67\times8=67\times\left(92+8\right)=67\times100=6700\\ 8\times23\times25\times125=\left(8\times125\right)\times\left(23\times25\right)=1000\times575=57500\)
a, ( 75 x 56 ) : 15 1175 : 25 + 1325: 25 + 466 x 25
= (75: 15) x 56 = ( 1175 + 1325) : 25 + 466 x 25
= 3 x 56 = 2500 : 25 + 466 x25
= 168 = 100 + 466 x 25
b, ( 80 x125 x10) : 25 = 25 x 4 + 466 x 25
= ( 80 x 10) x ( 125:25) = 25 x ( 4 + 466)
= 800 x 5 = 25 x 470
= 4 000 = 11750
d, ( 750 x 360 x 55) : ( 15 x 12 x 110)
= ( 75 x 360 x 550 ) : ( 15 x 12 x 110)
= (75 : 15 ) x ( 360 : 12) x ( 550 : 110)
= 5 x 30 x 5
= 25 x 30
= 750
a) (75 x 56) : 15
= 4200 : 15
= 280
b) (80 x 125 x 10) : 25
= 100 000 : 25
= 4000
c) 1175 : 25 + 1325 : 25 + 466 x 25
= (1175 : 25) + (1325 : 25) + (466 x 25)
= 47 + 53 + 11 650
= 11 750
d) (750 x 360 x 55) : (15 x 12 x 110)
= 14 850 000 : 19 800
= 750
\(=\dfrac{11}{12}\left(\dfrac{2}{7}+\dfrac{4}{7}+\dfrac{1}{7}\right)=\dfrac{11}{12}\cdot1=\dfrac{11}{12}\)
a, =12 x ( 45 + 55 )
= 12 x 100
= 1200
b, = 25 x 4 x 280
= 100 x 280
= 28000
c, = 268 x ( 192 -92)
= 268 x 100
= 26800
Câu 2: Tính bằng cách thuận tiện nhất:
\(a)\)\(12\times45+12\times55\)
\(=\)\(12\times\left(45+55\right)\)
\(=\)\(12\times100\)
\(=\)\(1200\)
\(b)\)\(25\times280\times4\)
\(=\)\(25\times4\times280\)
\(=\)\(100\times280\)
\(=\)\(28000\)
\(c)\)\(268\times192-92\times268\)
\(=\)\(268\times\left(192-92\right)\)
\(=\)\(268\times100\)
\(=\)\(26800\)