tính a, (x+2y)^2 b, (3x-2y)^2 c, (2x-1/2)^2 d, (x/2-y) (x/2+y) e, (x+1/3)^3 d, (x-2) (x^2+2x+4) 03/07/2021 Bởi Valentina tính a, (x+2y)^2 b, (3x-2y)^2 c, (2x-1/2)^2 d, (x/2-y) (x/2+y) e, (x+1/3)^3 d, (x-2) (x^2+2x+4)
Đáp án: a, `(x + 2y)^2 = x^2 + 2 . x . 2y + (2y)^2` ` =x^2 + 4xy +4y²` b, `(3x – 2y)^2 = (3x)² – 2 . 3x . 2y + (2y)^2` ` =9x^2 – 12xy +4y²` c, `(2x – 1/2)^2 = (2x)^2 – 2 . 2x . 1/2 + (1/2)^2` ` = 4x² – 2x + 1/4` d, `(x/2 – y)(x/2 + y) = (x/2)^2 – y^2` `=(x²)/4 – y^2` e, `(x+1/3)^3 = x³ +3 x² . 1/3 + 3x . (1/3)^2 + (1/3)³` `= x³ + x² + 1/3x + 1/27` f,`(x – 2)(x² + 2x + 4)` `=(x – 2)(x² + 2x + 2²)` `=(x – 2)³` Bình luận
Đáp án:
a, `(x + 2y)^2 = x^2 + 2 . x . 2y + (2y)^2`
` =x^2 + 4xy +4y²`
b, `(3x – 2y)^2 = (3x)² – 2 . 3x . 2y + (2y)^2`
` =9x^2 – 12xy +4y²`
c, `(2x – 1/2)^2 = (2x)^2 – 2 . 2x . 1/2 + (1/2)^2`
` = 4x² – 2x + 1/4`
d, `(x/2 – y)(x/2 + y) = (x/2)^2 – y^2`
`=(x²)/4 – y^2`
e, `(x+1/3)^3 = x³ +3 x² . 1/3 + 3x . (1/3)^2 + (1/3)³`
`= x³ + x² + 1/3x + 1/27`
f,`(x – 2)(x² + 2x + 4)`
`=(x – 2)(x² + 2x + 2²)`
`=(x – 2)³`
Đáp án đây ạ ! Chúc bạn học tốt !