a) Đặt \(x^2-y=a\) , ta có đa thức : \(3a^2+4a-15=\left(3a^2-5a\right)+\left(9a-15\right)=a\left(3a-5\right)+3\left(3a-5\right)=\left(a+3\right)\left(3a-5\right)\)

Thay \(x^2-y=a\)vào đa thức trên được : \(\left(x^2-y+3\right)\left(3x^2-3y-5\right)\)

b) \(12x^2-12xy+3y^2-20x+10y+8=\left(12x^2-6xy-12x\right)-\left(6xy-3y^2-6y\right)-\left(8x-4y-8\right)\)\(=6x\left(2x-y-2\right)-3y\left(2x-y-2\right)-4\left(2x-y-2\right)=\left(2x-y-2\right)\left(6x-3y-4\right)\)

(12x^2 - 12xy + 3y^2) - 10.(2x - y) + 8 

= 3(4x^2 - 4xy + y^2) - 10(2x - y) + 8 

= 3(2x - y)^2 - 10(2x - y) + 8 

= 3(2x - y)^2 - 10(2x - y) + 8 

= 3(2x - y)^2 - 6(2x - y) - 4(2x - y) + 8 

= 3(2x - y)(2x - y - 2) - 4(2x - y -2) 

= (2x - y -2)[3(2x - y) - 4] 

= (2x - y -2)(6x - 3y -4)

Ai k mk mk k lại

(12x^2 - 12xy + 3y^2) - 10.(2x - y) + 8 
= 3(4x^2 - 4xy + y^2) - 10(2x - y) + 8 
= 3(2x - y)^2 - 10(2x - y) + 8 
= 3(2x - y)^2 - 10(2x - y) + 8 
= 3(2x - y)^2 - 6(2x - y) - 4(2x - y) + 8 
= 3(2x - y)(2x - y - 2) - 4(2x - y -2) 
= (2x - y -2)[3(2x - y) - 4] 
= (2x - y -2)(6x - 3y -4)

Đề si thì phải 12x^2 - 12xy + 3y^2 

sai de

3*(\(4x^2-4xy+y^2\))-10(2x-y)+8

3*(2x-y)^2-10(2x-y)+8

3*(2x-y)^2-6(2x-y)-4(2x-y)+8

3(2x-y)(2x-y-2)-4(2x-y-2)

(2x-y-2)(6x-3y-40

\(\left(12x^2-12xy+3y^2\right)-10\left(2x-y\right)+8\)

\(=\left(12x^2-6xy-6xy+3y^2\right)-10\left(2x-y\right)+8\)

\(=\left[6x\left(2x-y\right)-3y\left(2x-y\right)\right]-10\left(2x-y\right)+8\)

\(=\left(2x-y\right)\left(6x-3y\right)-10\left(2x-y\right)+8\)

\(=3\left(2x-y\right)^2-10\left(2x-y\right)+8\)

Đặt \(2x-y=a\), khi đó biểu thức có dạng:

\(3a^2-10a+8=3a^2-6a-4a+8\)

\(=3a\left(a-2\right)-4\left(a-2\right)=\left(a-2\right)\left(3a-4\right)\)

\(=\left(2x-y-2\right)\left(6x-3y-4\right).\)

a) \(A=x^2-2xy+y^2+3x-3y-4\)

\(=\left(x-y\right)^2-1+3x-3y-3\)

\(=\left(x-y-1\right)\left(x-y+1\right)+3\left(x-y-1\right)\)

\(=\left(x-y-1\right)\left(x-y+1+3\right)\)

\(=\left(x-y-1\right)\left(x-y+4\right)\)

a: \(=\left(x+2\right)\left(x+3\right)\left(x-7\right)\left(x-8\right)-144\)

\(=\left(x^2-5x-14\right)\left(x^2-5x-24\right)-144\)

\(=\left(x^2-5x\right)^2-38\left(x^2-5x\right)+192\)

\(=\left(x^2-5x\right)^2-32\left(x^2-5x\right)-6\left(x^2-5x\right)+192\)

\(=\left(x^2-5x-32\right)\left(x^2-5x-6\right)\)

\(=\left(x^2-5x-32\right)\left(x-6\right)\left(x+1\right)\)

b: \(=\left(12x^2-12xy+3y^2\right)-20x+10y+8\)

\(=\left[3\left(2x-y\right)^2\right]-10\left(2x-y\right)+8\)

\(=3\left(2x-y\right)^2-4\left(2x-y\right)-6\left(2x-y\right)+8\)

\(=\left(2x-y\right)\left(6x-3y-4\right)-2\left(6x-3y-4\right)\)

\(=\left(6x-3y-4\right)\left(2x-y-2\right)\)