Đáp án: (9 x 8 – 12 – 5  12)  (4 + 5)

               = (72 – 12 – 60)   9

( 9 x 8 – 12 – 5 x 12 ) x ( 1 + 2 + 3 + 4 + 5 )

= ( 72 – 12 – 60 ) x ( 1 + 2 + 3 + 4 + 5)

= 0 x ( 1 + 2 + 3 + 4 + 5 )

= 0

1x2


















 

098

Đáp án:

( 9 x 8 – 12 – 5 x 12 ) x ( 1 + 2 + 3 + 4 + 5 )

= ( 72 – 12 – 60 ) x ( 1 + 2 + 3 + 4 + 5)

= 0 x ( 1 + 2 + 3 + 4 + 5 )

= 0

a,

b,

a. 4 x 126 x 25

= (4 x 25) x 126

= 100 x 126

= 12600

b. (9 x 8 – 12 – 5 x 12) x ( 1 + 2 + 3 + 4 + 5)

= (72 – 12 – 60) x ( 1 + 2 + 3 + 4 + 5)

= 0 x ( 1 + 2 + 3 + 4 + 5)

= 0

 Ta có thể đổi chỗ các phân số :

A)(7/12+5/12)+(4/9+1/3)+2=12/12+7/9+2=1+2+7/9=3+7/9=34/9

B)6/5*(3/8+5/8)-4/5=6/5*1-4/5=6/5-4/5=2/5

\((\)125-120\()\)x45

5x45=225

\(\dfrac{30x25x7x8}{75x8x12x14}\)=\(\dfrac{10\cdot1\cdot7\cdot1}{1\cdot1\cdot1\cdot12\cdot2}\)=\(\dfrac{70}{24}\)

`!`

\(a,\dfrac{8}{9}\times\dfrac{7}{5}-\dfrac{7}{9}\times\dfrac{2}{5}+\dfrac{2}{9}\\ =\dfrac{8}{9}\times\left(\dfrac{7}{5}-\dfrac{2}{5}\right)+\dfrac{2}{9}\\ =\dfrac{8}{9}\times\dfrac{5}{5}+\dfrac{2}{9}\\ =\dfrac{8}{9}+\dfrac{2}{9}\\ =\dfrac{10}{9}\)

\(b,\dfrac{5}{9}\times\dfrac{1}{4}+\dfrac{4}{9}\times\dfrac{3}{12}\\ =\dfrac{5}{9}\times\dfrac{1}{4}+\dfrac{4}{9}\times\dfrac{1}{4}\\ =\dfrac{1}{4}\times\left(\dfrac{5}{9}+\dfrac{4}{9}\right)\\ =\dfrac{1}{4}\times\dfrac{9}{9}\\ =\dfrac{1}{4}\)

a] 4/12 ; 5/12 ; 11/2 ; 1/4

b] 1 ; 9/12; 12/5 ; 11/3

c] 8/21; 6/11;8/7

d] 2/3 ;2/7 15/2

a]1/3  5/12     11/2       1/4

b]1      3/4         12/5         33/9

c]8/21      6/11        8/7

d]2/3        2/7          15/2

a) 1/3 ; 5/12 ; 11/2 ; 1/14

b) 1 ; 9/12 ; 12/5 ; 11/3

c) 8/21 ; 6/11 ; 8/7

d) 2/3 ; 2/7 ; 15/2