二次项系数不为一的十字相乘法6X^2-27X+12=-2x^2+3X+2=0.15A^2-8.5A-30=15X^2+14XY-8Y^2=9A^2B^2-6ABC^2-8C^2=2(X+Y)^2+3(X+Y)-20=
问题描述：
二次项系数不为一的十字相乘法
6X^2-27X+12=
-2x^2+3X+2=
0.15A^2-8.5A-30=
15X^2+14XY-8Y^2=
9A^2B^2-6ABC^2-8C^2=
2(X+Y)^2+3(X+Y)-20=
答
6X^2-27X+12=3(2x-1)(x-4)
-2x^2+3X+2= -(x-2)(2x+1)
0.15A^2-8.5A-30=0.05(A-60)(3A+10)
15X^2+14XY-8Y^2=(3X+4Y)(5X-2Y)
9A^2B^2-6ABC-8C^2=(3AB-4C)(3AB+2C)
2(X+Y)^2+3(X+Y)-20=(X+Y+4)(2X+2Y-5)