数学VII
3x2+5xy-2y2+x+9y-4 分解因式
∵3x^+x-4=(3x+4)(x-1) -2y^+9y-4=(-y+4)(2y-1) ∴3x^+5xy-2y^+x+9y-4=(3x-y+4)(x+2y-1)
3x^2+5xy-2y^2+x+9y-4首先按一个字母的幂排列 =3x^2+(5y+1)x+(-2y^2+9y-4) =3x^2+(5y+1)x-(2y-1)(y-4) =3x^2+[3(2y-1)+(-y+4)]x+(2y-1)(-y+4) =(3x-y+4)(x+2y-1)
原式=(x+2y)*(3x-y)+x+9y-4 =(x+2y-1)*(3x-y+4)
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