已知x+y=-2,xy=3,求2xy+x+y的值

1.已知x+y=-2,xy=3,求2xy+x+y的值
2xy+x+y
=2×3+(-2)
=4
2.已知2x²-5x+4=5,求式子（15x²-18x+4）-（-3x²+19x-32）-8x的值
（15x²-18x+4）-（-3x²+19x-32）-8x
=15x²+3x²-18x-19x-8x+4+32
=18x²-45x+36
=9(2x²-5x+4)
=9×5
=45
3.已知A=-3X²-2mx+3x+1,B=2x²+2mx-1,且2A+3B的值与x无关,求m的值
2A+3B
=2(-3X²-2mx+3x+1)+3(2x²+2mx-1)
=-6x²+6x²-4mx+6x+6mx-3
=(2m+6)x-3
2m+6=0
m=-3