Giúp mình với ah Bài 1 : tính a,(3-2y)^2 b,(3x+5y)^3 c,(6x-3y)^2 d,(3x+y^5 e,(2x-1)^3 f, 8x^3-y^3

Bài 1:

$a)(3-2y)^2_{}$

$⇔4y^2-12y+9_{}$

$b)(3x+5y)^3_{}$

$⇔(3x)^3+3.(3x)^2.5y+3.3x(5y)^2+(5y)^3_{}$

$⇔27x^3+3.9x^2.5y+3.3x.25y^2+125y^3_{}$

$⇔27x^3+135x^2y+225xy^2+125y^3_{}$

$+)Nếu_{}$ $(3x+5y)^2_{}$ $thì{}:$

$⇔(3x)^2+2.3x.5y+(5y)^2_{}$

$⇔9x^2+30xy+25y^2_{}$

$c)(6x-3y)^2_{}$

$⇔(6x)^2-2.6x.3y+(3y)^2_{}$

$⇔36x^2-36xy+9y^2_{}$

$d)(3x+y)^2_{}$

$⇔(3x)^2+2.3xy+y^2_{}$

$⇔9x^2+6xy+y^2_{}$

$e)(2x-1)^3_{}$

$⇔(2x)^3-3.(2x)^2.1+3.2x.1^2-1^3_{}$

$⇔8x^3-3.4x^2.1+3.2x.1-1_{}$

$⇔8x^3-12x^2+6x-1_{}$

$d)8x^3-y^3_{}$

$⇔2^3x^3-y^3_{}$

$⇔(2x)^3-y^3_{}$

$⇔(2x-y).[(2x)^2+2xy+y^2 ] _{}$

$⇔(2x-y)(4x^2+2xy+y^2)_{}$