Đáp án:
Giải thích các bước giải:
b8 a) 15 x 2121/4343 + 15 x 222222/434343
= 15x 21/43 + 15 x 22/43
=15x (21/43 + 22/43)
=15 x 43/43 =15
b) 16x25 + 44x100 / 29x96 +42x48
= 4x100 + 44x100 / 58x48+42x48
= 48x100 / 100x48 =1
c) 1994x1993 - 1992x1993 / 1992x1993 + 1994x7 + 1986
= (1994-1992) x 1993 / 1992x1993 + 1993x7+7+1986
= 2x1993 / 1992x1993 + 1993x7 + 1993
=2x1993 / 1993x8 =2/8 =1/4
b9. a)399x45+55x399 / 1995x1996-1991x1995
= 100x399 / 5x1995
= 100x399 / 5x5x399= 100/25=4
b)1996x1995-996 / 1000+1996x1994
= 1996x1994+1996-996 / 1000+1996x1994
= 1996x1994+1000 / 1000+1996x1994 = 1
c) 637x527 - 189 / 526x637 + 448
= 637x526 + 637-189 / 526x637 + 448
= 637x526 + 448 / 526x637+ 448=1
d)677x874 + 251 / 678x874 - 623
= 677x874 + 251 / 677x874 + 874-623
= 677x874 + 251 / 677x874 + 251=1
