A=123456.123457-123455.123458=(123455+1).123457-123455(123457+1)=123455.123457+123457-123455.123457-123455=2

B=987654.987655-987653.987656=(987653+1).987655-987653.(987655+1)=987653.987655+987655-987653.987655-987653=2

=> A=B

bằng nhau nhé

Bằng nhau nha bn

 tích mk mk tích lai cho nha bạn

Ta tính A = 123 456 . 123 457 - 123 455 . 123 458

                    = ( 123 455 + 1 ) . 123 457 - 123 455 . ( 123 457 + 1 )

                    = 123 457 . 123 455 + 123 457 - 123 455 . 123 457 + 123 455

                    = 0

Ta tính B = 987 654 . 987 655 - 987 653 . 987 656

              = ( 987 653 + 1 ) . 987 655 - 987 653 . ( 987 655 + 1 )

              = 987 655 . 987 653 + 987 655 - 987 653 . 987 655 + 987 653

               = 0

Vậy A = B

Ta có A = 123456.123457 - 123455.123458 

= (123455 + 1).123457 - 123455.123458

= 123455.123457 - 123455.123458 + 123457

= 123455(123457 - 123458) + 123457

= 123455.(-1) + 123457

= 2

Lại có B = 987654.987655 - 987653.987656

             = (987653 + 1).987655 - 987653.987656

             = 987653.987655 - 987653.987656 + 987655 

             = 987653.(987655 - 987656) + 987655

             = 987653.(-1) + 987655 = 2 

=> A = B (CÙNG = 2)

Ta có :

a = 123456.123458 = 123456 . ( 123457 + 1 ) = 123456 . 123457 + 123456

b = 123457 . 123457 = 123457 . ( 123456 + 1 ) = 123457 . 123456 + 123457

Mà 123456 < 123457 => 123456.123458 < 123457 . 123457 hay a < b 

Vậy a < b 

Đặt 123456=x và 987654=y. Theo bài ra , ta có:

-A= x(x+1)-(x-1)(x+2)=(x\(^2\)+x)-(x\(^2\)+2x-x-2)=x\(^2\)+x-x\(^2\)-2x+x+2=2.

-B=y(y+1)-(y-1)(x+2)=(y\(^2\)+y)-(y\(^2\)+2y-y-2)=y\(^2\)+y-y\(^2\)-2y+y+2=2.

\(\Rightarrow\)A=B.

Thấy đúng thì tick cho m nha

A = 123456 . 123457 - 123455 . 123458

A = ( 123456 - 123455 ) . ( 123458 - 123457 )

A = 1 . 1 

A = 1

B = 987654 . 987655 - 987653 . 987656 

B = ( 987654 - 987653 ) . ( 987656 - 987655 )

B = 1 . 1

B = 1 

Tk mk nhé!!!