Question

Answer 1

= [2.(x+y)]^2 - 2.2.(x+y) + 1^2

={[2.(x+y)]-1}^2

Answer 2

`#3107.101107`

`4(x + y)^2 - 4(x + y) + 1`

Đặt `a = 2(x + y)`

Ta có:

`4(x + y)^2 = 2^2 * (x + y)^2 = [ 2(x + y)]^2 = a^2` `(1)`

`4(x + y) = 2^2 * (x + y) = 2 * 2(x + y) * 1 = 2a` `(2)`

`1 = 1^2` `(3)`

Từ `(1), (2)` và `(3)`

`=> a^2 - 2a + 1 = (a - 1)^2`

Mà `a = 2(x + y)`

`=> [ 2(x + y) - 1]^2`