Bài 3. Tính nhanh: A.101² B.97.103 C.77²+ 23²+ 77.46 D.105²- 5²

`A, 101^2`

`=(100+1)^2`

`=100^2+2*100*1+1^2`

`=10000+200+1`

`=10201`

`B, 97*103`

`=(100-3)(100+3)`

`=100^2-3^2`

`=10000-9`

`=9991`

`C, 77^2+23^2+77*46`

`=77^2+2*77*23+23^2`

`=(77+23)^2`

`=100^2`

`=10000`

`D, 105^2-5^2`

`=(105-5)(105+5)`

`=100*110`

`=11000`