Giúp e bài 4. E camon nhiều

Bài `4:`

`a) 101^2`

`= (100^2 + 2 . 100 . 1 + 1^2)`

`= (10000 + 200 + 1)`

`= 10201`

`---------`

`b) 75^2 - 50 . 75 + 25^2`

`= 75^2 - 2 . 25 . 75 + 25^2`

`= (75-25)^2`

`= 50^2`

`= 2500`

`---------`

`c) 103 . 97`

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

`= 100^2 - 3^2`

`= 10000 - 9`

`= 9991`

`---------`

`d) 101^3`

`= 100^3 + 3 . 100^2 . 1 + 3 . 1^2 . 100 + 1^2`

`= 1000000 + 3000 + 300 + 1`

`= 1030301`

`---------`

`e) 99^3`

`= 100^3 - 3 . 100^2 . 1 + 3 . 1^2 . 100 - 1^3`

`= 1000000 - 30000 + 300 - 1`

`= 970299`

`---------`

`f) 98^3 + 6.98^2 +12.98+8`

`= 98^3 + 3 . 98^2 . 2 + 3 . 2^2 . 98 + 2^3`

`= (98+2)^3`

`= 100^3`

`= 1000000`

`---------`

`g) 13^3 - 9 . 13^2 + 27 . 13 - 27`

`= 13^3 - 3 . 13^2 . 3 + 3 . 3 . 13 - 3^3`

`= (13-3)^3`

`= 10^3`

`= 1000`