so sánh ơ bn

18/37+8/24+19/37

=(18/37+19/37)+8/24

=1+1//3

=4/3

18/37 +8/24+19/37 -1

=(18/37+19/37)+8/24-1

=1+8/24-1

=(1-1)+8/24

=0+8/24

=8/24

b) 23/24+3/8

=23/24+(3x3/8x3)

=23/24+9/24

=4/3

\(\left(\dfrac{18}{37}+\dfrac{19}{37}\right)+\left(\dfrac{8}{24}-\dfrac{47}{24}\right)+\dfrac{2}{3}=\dfrac{37}{37}-\dfrac{13}{8}+\dfrac{2}{3}=\dfrac{1}{24}\)

1) \(373737.73-37.737373\)

\(=37.10101.73-37.73.10101\)

\(=0\)

2) \(19.41414141-41.19191919\)

\(=19.41.1010101-41.19.1010101\)

\(=0\)

3) \(123456.456789456789-456789.123456123456\)

\(=123456.456789.1000001-456789.123456.1000001\)

\(=0\)

4) \(250.12.7\)

\(=250.4.3.7\)

\(=\left(250.4\right).\left(3.7\right)\)

\(=1000.21\)

\(=21000\)

5) \(24.125.9\)

\(=3.8.125.9\)

\(=\left(3.9\right).\left(8.125\right)\)

\(=27.1000\)

\(=27000\)

6) \(125.44.18\)

\(=125.4.11.2.9\)

\(=\left(125.4.2\right).\left(11.9\right)\)

\(=1000.99\)

\(=99000\)

7) \(8.24.6+12.4.52+2.22.24\)

\(=48.24+48.52+48.22\)

\(=48\left(24+52+22\right)\)

\(=48.98\)

\(=48\left(100-2\right)\)

\(=48.100-48.2\)

\(=4800-96\)

\(=4704\)

8) \(18.58.2-9.27.4+12.69.3\)

\(=36.58-36.27+36.69\)

\(=36\left(58-27+69\right)\)

\(=36.100=3600\)

9) \(30.85.3+18.72.5-45.37.2-9.20.10\)

\(=90.85+90.72-90.37-90.20\)

\(=90\left(85+72-37-20\right)\)

\(=90.100=9000\)

   18/37 + 8/24 + 19/37 - 1/23/24 + 2/3

= 18/37 + 19/37 +  1/3 + 2/3 - 1/23/24

= 1 + 1 - 1/23/24

= 2 - 1/23/24

= 1/24

( chú ý : 1/3 là rút gọn của 8/24 )

\(\frac{18}{37}+\frac{8}{24}+\frac{19}{37}-1\frac{23}{24}+\frac{2}{3}\)

\(=\frac{18}{37}+\frac{1}{3}+\frac{19}{37}-1\frac{23}{24}+\frac{2}{3}\)

\(=\left(\frac{18}{37}+\frac{19}{37}\right)+\left(\frac{1}{3}+\frac{2}{3}\right)-1\frac{23}{24}\)

\(=1+1-1\frac{23}{24}\)

\(=2-1\frac{23}{24}=\frac{1}{24}\)

\(\frac{18}{27}+\frac{8}{24}+\frac{19}{37}-1\frac{23}{24}+\frac{2}{3}\)

\(=\frac{18}{27}+\frac{8}{24}+\frac{19}{37}-\frac{47}{24}+\frac{16}{24}\)

\(=\left(\frac{18}{37}+\frac{19}{37}\right)+\left(\frac{8}{24}+\frac{16}{24}\right)-\frac{47}{24}\)

\(=\frac{37}{37}+\frac{24}{24}-\frac{47}{24}\)

\(=1+1-\frac{47}{24}\)

\(=2-\frac{47}{24}\)

\(=\frac{48}{24}-\frac{47}{24}\)

\(=\frac{1}{24}\)

mk ko biết

- (-15) – (-3 +15 – 8)

= 15 + 3 - 15 + 8 

= 11

 b) + ( - 143 + 17 – 35) – ( -143 + 37 – 35)

= -143 + 17 - 35 + 143 - 37 + 35 

= -20 

c) 50 - ( 47 + 50 - 18 ) -  ( 47 + 18 )

= 50 - 47 - 50 + 18 - 47 - 18 

= -47 - 47 

= -94 

d) 16 - ( -15 ) + ( -20 ) - | -24 | 

= 16 + 15 - 20 - 24 

= -13 

a, -(-15) - ( -3 + 15 - 8 ) = 15 - 3 + 15 + 8

                                      = 12 + 15 + 8

                                      = 27 + 8 

                                       = 35

b, + ( -143 + 17 - 35 ) - ( -143 + 37 - 35 )

=  -143 + 17 - 35 + 143 - 37 + 35

=  ( -143 + 143 ) + [ 17 + (-37 )] + ( -35 + 35)

=  0 + 20 + 0

= 20

c, 50 - ( 47 + 50 -18 ) - ( +47 + 18 )

= 50 - 47 - 50 + 18 - (-47) - 18

= ( 50 - 50 ) - [ 47 - (-47)] + (18 - 18 )

= 0 - 0 + 0

= 0

d, 16 - (-15) + (-20) -I -24 I

=  16 + 15 - 20 + 24

= 30 - 20 + 24

= 10 + 24

= 34 

e: \(=\left(\dfrac{18}{37}+\dfrac{19}{37}\right)+\left(\dfrac{8}{24}+\dfrac{2}{3}\right)-\dfrac{47}{24}=2-\dfrac{47}{24}=\dfrac{1}{24}\)

f: \(=-8\cdot\dfrac{1}{2}:\left(\dfrac{9}{4}-\dfrac{7}{6}\right)\)

\(=-4:\dfrac{13}{12}=\dfrac{-48}{13}\)

g: \(=\dfrac{4}{25}+\dfrac{11}{2}\cdot\dfrac{5}{2}-\dfrac{8}{4}=\dfrac{4}{25}+\dfrac{55}{4}-2=\dfrac{1191}{100}\)

áp dụng kiến thức tính nhanh ý

1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50=1275

= 1275

=1275

=1245

Có ai rảnh đâu mà đi ngồi cộng ngần đấy số ra.