\(9)(x+2y)^3\\=x^3+3\cdot x^2\cdot2y+3\cdot x\cdot(2y)^2+(2y)^3\\=x^3+6x^2y+12xy^2+8y^3\\---\\10)(2x+y)^3\\=(2x)^3+3\cdot(2x)^2\cdot y+3\cdot2x\cdot y^2+y^3\\=8x^3+12x^2y+6xy^2+y^3\\---\)
\(11)(3x-y)^3\\=(3x)^3-3\cdot(3x)^2\cdot y+3\cdot3x\cdot y^2-y^3\\=27x^3-27x^2y+9xy^2-y^3\\---\\12)(x-3y)^3\\=x^3-3\cdot x^2\cdot3y+3\cdot x\cdot(3y)^2-(3y)^3\\=x^3-9x^2y+27xy^2-27y^3\)
#\(Toru\)
Đúng 0
Bình luận (2)