已知A=-x²+5xy-4x+2,B=-2x²-3xy-1.（1）求4A-2B的值；（2）如4A-2B的值与x无关,求y的值

已知A=-x²+5xy-4x+2,B=-2x²-3xy-1.（1）求4A-2B的值；（2）如4A-2B的值与x无关,求y的值
已知A=-x²+5xy-4x+2,B=-2x²-3xy-1.（1）求4A-2B的值；（2）如4A-2B的值与x无关,求y的值

已知A=-x²+5xy-4x+2,B=-2x²-3xy-1.（1）求4A-2B的值；（2）如4A-2B的值与x无关,求y的值
1)4A-2B
=4(-x²+5xy-4x+2)-2(-2x²-3xy-1)
=-4x²+20xy-16x+8+4x²+6xy+2
=26xy-16x+10
2)4A-2B=26xy-16x+10=x(26y-16)+10
若与x无关,在26y-16=0,y=8/13

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4A-2B=4(-X^2+5XY-4X+2)-2(-2X^2-3XY-1)
=-4X^2+20XY-16X+8+4X^2+6XY+2
=26XY-16X+10
=(26Y-16)X+10
与X无关,则有26Y-16=0,即有Y=8/13

1) 4A - 2B = 4(-x²+5xy-4x+2) - 2(-2x²-3xy-1)
= 26xy - 16x + 10
= 2x(13y - 8) + 10
2) 因(4A - 2B )的值与x无关，故 13y - 8 = 0，所以y = 8/13.