分解因式: 3x2+5xy-2y2+x+9y-4 答案 因为3x2+5xy-2y2=⎛ ⎛⎜ ⎜⎝⎞⎟⎠3x-y⎛ ⎛⎜ ⎜⎝⎞⎟⎠x+2y,所以设3x2+5xy-2y2+x+9y-4=(3x-y+a)(x+2y+b) =3x2+5xy-2y2+ax+2ay+3bx-by+ab =3x2+5xy-2y2+(a+3b)x+(2a-b)y+ab ,所以⎧⎪⎪⎨...
解答:解:3x2+5xy-2y2+x+9y-4 =(3x-y)(x+2y)+x+9y-4 =(3x-y)(x+2y)-(3x-y)+4x+8y-4 =(3x-y)(x+2y-1)+4(x+2y-1) =(3x-y+4)(x+2y-1). 点评:此题主要考查了因式分解,熟练利用十字相乘法以及拆项法因式分解是解题关键. ...
3x2+5xy−2y2+x+9y−4= .相关知识点: 试题来源: 解析 (x+2y−1)(3x−y+4) 3x2+5xy−2y2+x+9y−4 =(3x−y)(x+2y)+x+9y−4 =(3x−y)(x+2y)−(3x−y)+4x+8y−4 =(3x−y)(x+2y−1)+4(x+2y−1) =(3x−y+4)(x+2y−1).反馈...
3x2+5xy-2y2+x+9y-4 =（3x-y）（x+2y）+x+9y-4 =（3x-y）（x+2y）-（3x-y）+4x+8y-4 =（3x-y）（x+2y-1）+4（x+2y-1）=（3x-y+4）（x+2y-1）．,9,
3x²+5xy-2y²+x+9y-4 =(3x-y)(x+2y)+x+9y-4 =(3x-y+4)(x+2y-1)
[完全解答]解法一:由于 3x^2+5xy-2y^2=(3x-y)(x+2y) .故可设 3x2+5ry-2y2+x+9y-4=(3r-y+a)(r+2y+b) =3.r2+5.ry-2y2+(a+3b).r+(2a b)y+ab. a+3b=1,① 比较两边系数,得: 2a-b=9,② ab=-4.③ a=4, 由①、 解得: b=-1. 将a=4.b=-1代入③式成立. ∴原式...
解答 解:①3x2+5xy-2y2+x+9y-4=(3x-y)(x+2y)+x+9y-4=(3x-y)(x+2y)-(3x-y)+4x+8y-4=(3x-y)(x+2y-1)+4(x+2y-1)=(3x-y+4)(x+2y-1);②x2-2xy-3y2+3x-5y+2=(x-3y)(x+y)+3x-5y+2=(x-3y)(x+y)+(x+y)+2x-6y+2=(x+y)(x-3y+1)+2(x-3y+1)=(x+y+...
3x2+5xy-2y2+x+9y-4 答案 解:原式=(3x-y)(x+2y)+x+9y-4 =(3x-y)(x+2y)-(3x-y)+4x+8y-4 =(3x-y)(x+2y-1)+4(x+2y-1) =(3x-y+4)(x+2y-1) 故答案为:(3x-y+4)(x+2y-1) 根据因式分解的一般步骤,将前三项运用数字相乘法分解,然后几项进行拆项,提取公因式,就很容易作答...
3x -y 4 x 2y -1 双十字因式分解~~~得：3x^2+5xy-2y^2+x+9y-4 =(3x-y+4)(x+2y-1)
又十字相乘法：先按十字相乘法分解二次项：3X -Y × X 2Y 然后考虑常数项配合进去后，一次项也满足条件：4 3X -Y × X 2Y -1 ∴原式=(3X-Y+4)(X+2Y-1)