Tính nhẩm

9 x 6 = ......        9 x 7 = ......        9 x 5 = ......        9 x 8 = ......

54 : 9 = .....        63 : 9 = .....        45 : 9 = .....        72 : 9 = .....

54 : 6 = .....        63 : 7 = .....        45 : 5 = .....        72 : 8 = .....

Tính nhẩm:

9 x 5 =

9 x 6 =

9 x 7 =

9 x 8 =

45 : 9 =

54 : 9 =

63 : 9 =

72 : 9 =

45 : 5 =

54 : 6 =

63 : 7 =

72 : 8 =

3+2+6+9+8+7+54+10=

Tính nhẩm:

6 x 6 = ...              7 x 9  = ...             8 x 7 = ...               9 x 6 =...

48 : 6 =...              54 : 6 = ...             42 : 6 = ...             63 : 7 = ...

Tính nhẩm:

6 x 6 = ...              7 x 9  = ...             8 x 7 = ...               9 x 6 =...

48 : 6 =...              54 : 6 = ...             42 : 6 = ...             63 : 7 = ...

1+2+3+4+5+6+7+8+9+0+1+2+3+4+5+6+7+8+9+9+8+7+6+5+4+3+2+1+1+34+4+6+7+8+97+6+4+3+32+4+57+7+8+8+6+65+4+3+3+46+7+8+7+64+3+3+5+68+8+6+3+3+5+78+8+6+54+5+7+8+852+3+5+89+8+5+45+7×9×9×9×9×9×9×9×9×9×9×9×8×8×7×9×9×7×7×87×7×8×7×7×8×7×7×8

\(\frac{6+a}{9-a^2}+...=\frac{6}{9-a^2}+...+\frac{a^2}{9a-a^3}\ge\frac{54}{27-a^2-b^2-c^2}+\frac{\left(a+b+c\right)^2}{9\left(a+b+c\right)-\left(a^3+b^3+c^3\right)}\)

\(\ge\frac{54}{27-2\left(a+b+c\right)+3}+\frac{9}{27-3\left(a+b+c\right)+6}=\frac{54}{24}+\frac{9}{24}=\frac{21}{8}\)

Tính nhẩm:

6 x 6 =

6 x 9 =

6 x 7 =

6 x 8 =

36 : 6=

54 : 6 =

42 : 6 =

48 : 6 =