Ответ:

1.

98*102=(100-2) (100+2) =100²-2²=10000-4=9996

2.

77*83=(80-3) (80+3) =80²-3²=6400-9=6391

3.

9,9*10,1= (10-0,1) (10+0,1) =10²-0,1²=99,99

4.

10,5*9,5=(10+0,5) (10-0,5) =10²-0,5²=99,75

5. 74*66=(70+4) (70-4) =70²-4²=4900-16=4884

Ответ:

1)(100-2)(100+)=100²-2²=10000-4=9996

2)(80-3)(80+3)=80²-3²=6400-9=6391

3)(10-0,1)(10+0,1)=10²-0,1²=100-0,01=99,99

4)(10+0,5)(10-0,5)=10²-0,5²=100-0,25=0,75

5)(70+4)(70-4)=70²-4²=4900-16=4884