Question

khai triển các hằng đẳng thức sau
1.(2x+y)²
2.(x-2y)²
3.(2x-3y)²
4.(z+2f)²
5.(x+3)²
6.(y-7)²
7.(2x-3)²
giúp mik zới ak

 

Answer 1

`1)`

`(2x+y)^2=(2x)^2 + 2.2x.y + y^2`

`=4x^2 + 4xy + y^2`

`2)`

`(x-2y)^2=x^2 - 2.x.2y + (2y)^2`

`= x^2 - 4xy + 4y^2`

`3)`

`(2x-3y)^2=(2x)^2 - 2.2x.3y + (3y)^2`

`=4x^2 - 12xy + 9y^2`

`4)`

`(z+2f)^2=z^2 + 2.z.2f + (2f)^2`

`= z^2 + 4xf + 4f^2`

`5)`

`(x+3)^2=x^2 + 2.x.3 + 3^2`

`=x^2 + 6x + 9`

`6)`

`(y-7)^2=y^2 - 2.y.7 + 7^2`

`= y^2-14y+49`

`7)`

`(2x-3)^2=(2x)^2 - 2.2x.3 + 3^2`

`=4x^2 - 12x + 9`