3x²＋5xy-2y²＋x＋9y-4因式分解啊~

3x²＋5xy-2y²＋x＋9y-4因式分解啊~
3x²＋5xy-2y²＋x＋9y-4因式分解啊~

3x²＋5xy-2y²＋x＋9y-4因式分解啊~
3x²＋5xy-2y²＋x＋9y-4
=(3x-y)(x+2y)+4x+8y-3x+y-4
=(3x-y+4)(x+2y)+-3x+y-4
=（3x-y+4)(x+2y-1）

3x²＋5xy-2y²＋x＋9y-4
=3(x²+2xy+y²)-xy-5y²+x+9y-4
=3(x+y)²-y(x+5y)+5y+x+4y-4
=3(x+y)²+(x+5y)(1-y)+4(y-1)
=3(x+y)²+(y-1)(x+5y-4)

3X^2+5XY-2Y^2+X+9Y-4=(X+2Y)(3X-Y)+(X+9Y)-4=(X+2Y-1)(3x-y+4)双十字相乘法