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
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![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](/uploads/image/z/995010-42-0.jpg?t=%E5%B7%B2%E7%9F%A5A%3D-x%26%23178%3B%2B5xy-4x%2B2%2CB%3D-2x%26%23178%3B-3xy-1.%EF%BC%881%EF%BC%89%E6%B1%824A-2B%E7%9A%84%E5%80%BC%EF%BC%9B%EF%BC%882%EF%BC%89%E5%A6%824A-2B%E7%9A%84%E5%80%BC%E4%B8%8Ex%E6%97%A0%E5%85%B3%2C%E6%B1%82y%E7%9A%84%E5%80%BC)
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
tge6tyh
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.