theo cách cấp 2

A=(10001x2012+1)x(10001x2013-1) - 10001²x2012x2013

=10001²x 2012 x 2013 - 2012 x 10001 + 10001 x 2013 - 1 - 10001² x 2012 x 2013

= 10001 x ( 2012 + 2013 )-1

=40254025 - 1

= 40254024

Đúng hay không tui không biết ha

\(A=20122013x20132012-20122012x20132013\)\(=10000\)

a: =-5/21

b: \(=\dfrac{15}{4}-\dfrac{9}{4}=\dfrac{6}{4}=\dfrac{3}{2}\)

c: \(=\left(\dfrac{31}{10}-\dfrac{25}{10}\right)\cdot3-2=\dfrac{6}{10}\cdot3-2=\dfrac{18}{10}-\dfrac{20}{10}=\dfrac{-2}{10}=\dfrac{-1}{5}\)

d: \(=\dfrac{4}{3}\cdot\dfrac{1}{20}=\dfrac{4}{60}=\dfrac{1}{15}\)

a: \(=\dfrac{-15}{25}\cdot\dfrac{8}{16}=\dfrac{-3}{5}\cdot\dfrac{1}{2}=\dfrac{-3}{10}\)

b: \(=\dfrac{2}{3}+\dfrac{2}{7}=\dfrac{20}{21}\)

c: \(=\dfrac{3}{2}\cdot\dfrac{-3+2}{4}=\dfrac{3}{2}\cdot\dfrac{-1}{4}=\dfrac{-3}{8}\)

d: \(=\dfrac{7}{11}\cdot\dfrac{11}{7}\cdot\dfrac{-3}{41}=-\dfrac{3}{41}\)

60b

61b

62a

63c

64b

65b

66d

67b

68b

\(a,\dfrac{10}{11}+\dfrac{3}{11}:3-\dfrac{1}{7}=\dfrac{10}{11}+\dfrac{3}{11}.\dfrac{1}{3}-\dfrac{1}{7}=\dfrac{10}{11}+\dfrac{1}{11}-\dfrac{1}{7}=1-\dfrac{1}{7}=\dfrac{6}{7}\\ b,\dfrac{-3}{7}+\dfrac{5}{13}+\dfrac{3}{7}=\left(\dfrac{-3}{7}+\dfrac{3}{7}\right)+\dfrac{5}{13}=\dfrac{5}{13}\\ c,-\dfrac{3}{13}+\dfrac{7}{12}-\dfrac{10}{13}+\dfrac{5}{12}=\left(-\dfrac{3}{13}-\dfrac{10}{13}\right)+\left(\dfrac{7}{12}+\dfrac{5}{12}\right)=\left(-1\right)+1=0\)

\(d,\dfrac{5}{3}.\dfrac{7}{25}+\dfrac{5}{3}.\dfrac{21}{25}-\dfrac{5}{3}.\dfrac{7}{25}=\left(\dfrac{5}{3}.\dfrac{7}{25}-\dfrac{5}{3}.\dfrac{7}{25}\right)+\dfrac{5}{3}.\dfrac{3.7}{5.5}=\dfrac{7}{5}\)

8c

9b

10d

11d

12b

13b

14b

15c

16a

34 B

35 C

36 A

37 B

38 A

40 A

66 C

34b

35c

36a

37b

38c

39c

40b

66c

1c

2c

3b

4d

5b

6d

7a