若关于x,y的整式(ax²+2xy-3y²+1)-(4x²+y³-bxy-8)的值与x的取值无关.↙.求整式9(a-b)-[8ab-3(a-b)]-4[(a-b)-5ab]的值
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![若关于x,y的整式(ax²+2xy-3y²+1)-(4x²+y³-bxy-8)的值与x的取值无关.↙.求整式9(a-b)-[8ab-3(a-b)]-4[(a-b)-5ab]的值](/uploads/image/z/5127333-69-3.jpg?t=%E8%8B%A5%E5%85%B3%E4%BA%8Ex%2Cy%E7%9A%84%E6%95%B4%E5%BC%8F%EF%BC%88ax%26%23178%3B%2B2xy-3y%26%23178%3B%2B1%29-%284x%26%23178%3B%2By%26%23179%3B-bxy-8%29%E7%9A%84%E5%80%BC%E4%B8%8Ex%E7%9A%84%E5%8F%96%E5%80%BC%E6%97%A0%E5%85%B3.%E2%86%99.%E6%B1%82%E6%95%B4%E5%BC%8F9%28a-b%29-%5B8ab-3%28a-b%29%5D-4%5B%28a-b%29-5ab%5D%E7%9A%84%E5%80%BC)
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若关于x,y的整式(ax²+2xy-3y²+1)-(4x²+y³-bxy-8)的值与x的取值无关.↙.求整式9(a-b)-[8ab-3(a-b)]-4[(a-b)-5ab]的值
若关于x,y的整式(ax²+2xy-3y²+1)-(4x²+y³-bxy-8)的值与x的取值无关.↙
.求整式9(a-b)-[8ab-3(a-b)]-4[(a-b)-5ab]的值
若关于x,y的整式(ax²+2xy-3y²+1)-(4x²+y³-bxy-8)的值与x的取值无关.↙.求整式9(a-b)-[8ab-3(a-b)]-4[(a-b)-5ab]的值
解
原式
=(ax²-4x²)+(2xy+bxy)-3y²-y³+(1+8)
=(a-4)x²+(2+b)xy-3y²-y³+9
与x值无关
∴a-4=0,2+b=0
∴a=4,b=-2
∴原式
=9(a-b)-8ab+3(a-b)-4(a-b)+20ab
=(9+3-4)(a-b)+(20ab-8ab)
=8(a-b)+12ab
=8(4+2)+12×4×(-2)
=48-96
=-48
要使等式的取值与x无关,则关于x的项应该全部消掉。所以,a=4,b=-2
因此,带入所求的式子=9x6-(-64-18)-4(6+40)
=54+82-184
=136-184
=-48