Toán Lớp 8: giúp với ạ phân tích đa thức thành nhân tử a)3x^2-6xy+3y^2 b)4x^2-6y+8xy-3x c)16x^3+54y^3 d)2xy+1/4-x^2-y^2 e)x^3-y^3-3x^2+3x-1 f)4x^2y

Question

Toán Lớp 8:  giúp với ạ phân tích đa thức thành nhân tử a)3x^2-6xy+3y^2 b)4x^2-6y+8xy-3x c)16x^3+54y^3 d)2xy+1/4-x^2-y^2 e)x^3-y^3-3x^2+3x-1 f)4x^2y-6xz-4xy+y+3z

maingoctruc · Answer

a)3x&sup2;-6xy+3y&sup2;           =3(x&sup2;-xy+y&sup2;)           =3(x-y)&sup2;           b)4x&sup2;-6y+8xy-3x           =(4x&sup2;+8xy)+(-6y-3x)           =4x(x+2y)-3(x+2y)           =(x+2y).(4x-3)           c)16x&sup3;+54y&sup3;           =2(8x&sup3;+27y&sup3;)           =2[(2x)&sup3;+(3y)&sup3;]           =2.(2x+3y).[(2x&sup2;)-2x.3y+(3y)&sup2;]           d)2xy+1/4-x&sup2;-y&sup2;           =-(x&sup2;-2xy+y&sup2;)+1/4           =-(x-y)&sup2;+(1/2)&sup2;           =-(x-y+1/2).-(x-y-1/2)               e)x&sup3;-y&sup3;-3x&sup2;+3x-1           =( x&sup3;-3x&sup2;+3x-1)-y&sup3;           =(x-1)&sup3;-y&sup3;           =[(x-1)-y].[(x-1)&sup2;+(x-1).y+y&sup2;]            f)4x&sup2;y-6xz-4xy+y+3z           =(4x&sup2;y-4xy)+(-6xz+3z)+y           =4xy(x-1)-3z(x-1)+y           =(x-y).(4xy-3z+y)