B = 454 . 138 - 110
B = ( 454 - 1 )(137 + 1) - 110
B = 454 . 137 + 454 - 137 - 1 - 110
B = 454 . 137 + 206 = A
=> B = A ( Đpct )
Ta có: A= 137 . 454 + 206
= 454 . 137 + 206
= ( 453 + 1) . 137 + 206
= 453.137 + 137 + 206
= 453.137 +343
Ta có: B= 453.138 - 110
= 453 . (137 + 1) - 110
= 453 . 137 + 453 - 110
= 453 . 137 + 343
=> A=B (đpcm)