x y=a,x-y=b,那么x²-y²等于?
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解题思路:根据题目条件,由集合的知识可求解题过程:varSWOC={};SWOC.tip=false;try{SWOCX2.OpenFile("http://dayi.prcedu.com/inclu
1.=3(a-b)/(10ab)*(25a^2b^3)/((a+b)(a-b))=15/2*(ab^2)/(a+b)2.=(x+2y)(x-2y)/(x+y)^2*2x(x+y)/(x+2y)=2x(
是不是-2A+B=2a所以-4x²+6xy-2y²+2x-4y+4x²-6xy+2y²+3x-y=5x-5y=5a+15=2aa=-3A=18-27+9+3-6
原式既为Bx-xy-AB+Ay=x^2-9xy+8y^2,则A=xB=8y
定义域xy≠0因为A=B所以(xy-1)/xy=0得xy=1所以此时A={x,1,0}①若y=1,代入xy=1解得x=1,此时A={1,1,0}违反集合的互异性,舍去②若|x|=1,解得x=±1(1)
1/2x²+xy+1/2y²=½﹙x+y﹚²=½再问:还有(-a+b)(a-b)=再答:(-a+b)(a-b)=-(a-b)²=-a
xy/(x+y)=2∴xy=2(x+y)(3xy-x-y)/(3x-5xy+3y)=[6(x+y)-x-y]/[3x+3y-10(x+y)]=5(x+y)/[-7(x+y)]=-5/7
当y=xy时,且y=0时,则x^2=1,x=x,所以x=-1当y不为0时,x=1,因为集合中的元素都有其单一性,所以不成立.当x^2=y时,xy=1,所以y=1,x=1.违反集合中元素单一性,不成立.
A-[B-(-2B+A]=A-(B+2B-A)=A-3B+A=2A-3B=2(3X²-XY+Y²)-3(2X²-3XY-2Y²)=6X²-2XY+2Y
4A+B-(A-B)=4A+B-A+B=3A+2B=3(x^2+xy+y^2)+2(x^2-xy+y^2)=3x^2+3xy+3y^2+2x^2-2xy+2y^2=5x^2+xy+5y^2=(x^2+
原式=4A+B-A+B=3A+2B=3x²+3xy+3y²+2x²-2xy+2y²=5x²+xy+5y²=(x²+3xy+4y
再问:-ab(a-b)²+a(b-a)²-ac(a-b)²再答:
2(x+xy)-[(xy-3y)-x]-(-xy)=2x+2xy-xy+3y+x+xy=3x+3y+2xy=3(x+y)+2xy=3*(-2)+2*3=0
A+B=(x²-3xy+y²)+(2x²+xy-9y²)=x²-3xy+y²+2x²+xy-9y²=3x²-2
设A=2x²-3xy+y²-x+2y,B=4x²-6xy+2y²-3x-y,且B-2A=a所以a=B-2A=4x²-6xy+2y²-3x-y
√ab=√24再问:xy的呢?知道答案嘛再答:不
∣x-2a∣+(y+3)²=0因为∣x-2a∣≥0,(y+3)²≥0所以∣x-2a∣=0,(y+3)²=0所以x=2a,y=-3B-2A=(4x²-6xy+2y
2A-3B=2(3x²-xy+y²)-3(2x²-3xy-2y²)=6x²-2xy+2y²-6x²+9xy+6y²=7x
⑴因为xy/x-y=2,把x、y的值都扩大到原来的5倍所以2xy/(x-y)=2×5x×5y/(5x-5y)=10xy/(x-y)又因为xy/(x-y)=2所以2xy/x-y=20⑵1/(b²