A<B

A = a5c6 + 1d7d 

= a x 1000 + 500 + c x 10 + 6 + 4000+b x1 00 + 70 + d 

= abcd + 4576 

mà B = abcd + 4567 

=> A > B

A = a5c6 + 4b7d 

=> A = 1000a + 10c + 500 + 6 + 4000 + 100b + 70 + d

B = abcd + 4567

=> B = 1000a + 100b + 10c + d + 4567

ta thấy có những gì giống nhau thì rút gọn

=> A = 500 + 6 + 70 + 4000 = 4576

=> B = 4567

Vậy A > B

A = 1000a + 500 + 10c + 6 + 4000 + 100b + 70 + d

A = 1000a + 100b + 10c + d + 4576

A = abcd + 4576

=> A > B

A=1000xa+500+10xc+4000+100xb+70+d=(1000xa+100xb+10xc+d)+4570=abcd+4570

=> A>B

A = a5c6 + 4b7d 

=> A = 1000a + 10c + 500 + 6 + 4000 + 100b + 70 + d

B = abcd + 4567

=> B = 1000a + 100b + 10c + d + 4567

ta thấy có những gì giống nhau thì rút gọn

=> A = 500 + 6 + 70 + 4000 = 4576

=> B = 4567

=> A > B

Vậy  chọn   C.   B  >  A  

\(\text{Xét theo cấu tạo số, ta có:}\)
\(\text{A = 1000a + 100b + 10c + d + 500 + 6 + 4000 + 70}\)
\(\text{A = 1000a + 100b + 10c + d + 4576}\)
\(\text{B = 1000a + 100b + 10c + d + 4567}\)
\(\text{Suy ra:}\)\(A>B\)

A=1000a+500+10c+6+4000+100b+70+d

A=1000a+100b+10c+d+4000++500+70+6

A=1000a+100b+10c+d+4576

B=1000a+100b+10c+d+4567

suy ra A>B

so sanh A=a5c6+4b7d va B=abcd+4567

A=B A>B A<B B>A

A =a05c6 + 4b7d = 0506 + 4070 + a000 = c0 + b00  + d + abcd = 4576 + abcd 

=> A > B 

\(A=1000a+500+10c+6+4000+100b+70+d\)

\(=1000a+100b+10c+d+4576\)

=B

B

B