24 : 6 : 2 = 24 : 3 = 8 => S

2/3-(1/6+1/8)=2/3-(4/24+3/24)=2/3-7/24=16/24-7/24=9/24=3/8

2/3 - (1/6 + 1/8) = 2/3 -(4/24 + 3/24) = 2/3 - 7/24 = 16/24 - 7/24 = 9/24 = 3/8

**** CHO MK NHA

-1x 5 + 11 = 6

1-2+3-4+5-6+7-8+9-10+11

= ( 1-2 ) + (3-4 ) + ( 5-6 ) + ( 7-8 )  + ( 9-10 ) + 11

= (-1)    + (  -1)   +   (-1 )   +   ( -1)    +    ( -1)     + 11

= (-1) x 5 + 11

=(-5) + 11

=6

2/7;1/3;3/5;7/8;4/3

là 2/7, 1/3, 3/5, 7/8, 4/3

1) 1/3 x 1/2 x 3/7 = 3/42 = 1/14

2) 5/4 x 1/3 +1/7 = 5/12 + 1/7 = 35/84 + 12/84 = 47/84

3) 8 x ( 8/9 - 2/3 ) = 8 x 2/9 = 16/9

4) 5/6 x 48/20 x 1/2 = 240/240 = 1

5) ( 2/5 + 3/4 ) + 8 = 23/20 + 8 = 23//20 + 160/20 = 183/20

6) 10 x ( 1/2 - 1/5 ) = 10 x 3/10 = 10/1 x 3/10 = 30/10 = 3

a) 13,6 + 14,5 + 15,4 - 4,6 - 5,5 - 6,4 

= (13,6 - 4,6) + (14,5 - 5,5) + (15,4 - 6,4)

= 9 + 9 + 9

= 9 . 3

= 27.

b) 7/8 x 1/2 + 7/8 x 3/2 - 7/8 x 2

= 7/8 x (1/2 + 3/2 - 2)

= 7/8 x 0 = 0

a) 13,6 + 14,5 + 15,4 - 4,6 - 5,5 - 6,4 = 13,6 - 4,6 + 14,5 - 5,5 + 15,4 - 6,4

                                                      =  9 + 9 + 9

                                                      = 9.3 = 27.

b) \(\frac{7}{8}.\frac{1}{2}+\frac{7}{8}.\frac{3}{2}-\frac{7}{8}.2=\frac{7}{8}.\left(\frac{1}{2}+\frac{3}{2}-2\right)\)

                                               \(=\frac{7}{8}.0\)

                                               \(=0.\)

2/7;1/3;3/5;7/8;4/3

kick mik nha!

a, Cách 1 : \(x^2+5x+6=x^2+2x+3x+6=\left(x+2\right)\left(x+3\right)\)

Cách 2 : \(x^2+5x+6=x^2+2.\frac{5}{2}x+\frac{25}{4}-\frac{25}{4}+6\)

\(=\left(x+\frac{5}{2}\right)^2-\frac{1}{4}=\left(x+2\right)\left(x+3\right)\)

b, Cách 1 : \(x^2-x-6=x^2+2x-3x-6=\left(x-3\right)\left(x+2\right)\)

Cách 2 : \(x^2-x-6=x^2-x+\frac{1}{4}-\frac{1}{4}-6=\left(x-\frac{1}{2}\right)^2-\frac{25}{4}=\left(x-3\right)\left(x+2\right)\)

c, Cách 1 : \(x^2+6x+8=x^2+4x+2x+8=\left(x+2\right)\left(x+4\right)\)

Cách 2 : \(x^2+6x+8=x^2+6x+9-1=\left(x+3\right)^2-1=\left(x+2\right)\left(x+4\right)\)

d, Cách 1 : \(x^2-2x-8=x^2+2x-4x-8=\left(x-4\right)\left(x+2\right)\)

Cách 2 : \(x^2-2x-8=x^2-2x+1-9=\left(x-1\right)^2-9=\left(x-4\right)\left(x+2\right)\)

1+2+3+4+5+6+7+8+9=?

= (1+9)+ (2+8)+ (3+7)+(4+6)+(5+5)

= 10+10+10+10+10

=50

Hok tốt !!!!!

1+2+3+4+5+6+7+8+9

=(1+9)+(2+8)+(3+7)+(4+6)+5

=10+10+10+10+5

=45

Xin lỗi mik nhìn nhầm 

=45