这个怎么分解因式？

分解因式1,分解因式X²+4Y²+9Z²+4XY-6XYZ-12YZ 2,分解因式2X²+7XY+3Y²+9X+2Y-5

1。原式=x^2+4y^2+9z^2+4xy-6zx-12yz ??? =(x^2+4xy+4y^2)-(6zx+12yz)+9z^2 =(x+2y)^2-6z(x+2y)+(3z)^2 =(x+2y-3z)^2 2。 原式=2x^2+7xy+3y^2+9x+2y-5 =2x^2+(7y+9)x+(3y^2+2y-5) =2x^2+(7y+9)x+(3y+5)(y-1) =2x^2+[2(3y+5)+(y-1)]x+(3y-5)(y-1) =2x^2+2x(3y+5)+(y-1)x+(3y+5)(y-1) =2x[x+(3y+5)]+(y-1)[x+(3y+5)] =(x+3y+5)(2...全部

  1。原式=x^2+4y^2+9z^2+4xy-6zx-12yz ??? =(x^2+4xy+4y^2)-(6zx+12yz)+9z^2 =(x+2y)^2-6z(x+2y)+(3z)^2 =(x+2y-3z)^2 2。
  原式=2x^2+7xy+3y^2+9x+2y-5 =2x^2+(7y+9)x+(3y^2+2y-5) =2x^2+(7y+9)x+(3y+5)(y-1) =2x^2+[2(3y+5)+(y-1)]x+(3y-5)(y-1) =2x^2+2x(3y+5)+(y-1)x+(3y+5)(y-1) =2x[x+(3y+5)]+(y-1)[x+(3y+5)] =(x+3y+5)(2x+y-1)。
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