作业帮16-24(x-y) 9(x-y)
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=cov（9x,x-y）+cov(y,x-y)=9cov(x,x)-9cov(x,y)+cov(x,y)-cov(y,y)
1/9x^2-10/9xy+y^2-(1/9x^2-y^2)=-10/9xy+2y^2=2y(y-5/9x)
原式=(x-y)[(x-y)^2-6(x-y)+9]=(x-y)(x-y-3)^2很高兴为您解答,祝你学习进步!不懂可追问!
x＞0,y＞0,a＞0 a(x+y)≤√(x²+y²) a²(x+y)²≤x²+y² (1-a²)(x²+y
(x+y)(x+y-6)+9=(x+y)^2-6(x+y)+9=((x+y)-3)^2=(x+y-3)^2x²-16y²-x-4y=(x+4y)(x-4y)-(x+4y)=(x+4
区域是一个正方形
第一种：用平方差公式,原式=(x+y)^2-(4(x-y))^2=(x+y-4(x-y))(x+y+4(x-y))=(5y-3x)(5x-3y)第二种：全展开合并同类项,原式=x^2+y^2+2xy-
解题思路：化简解答解题过程：varSWOC={};SWOC.tip=false;try{SWOCX2.OpenFile("http://dayi.prcedu.com/include/readq.ph
1.(x-y)(x+y)+(x-y)+(x+y)=x²-y²+x²-y²=2x²-2y²2.x(x+2)-(x+1)(x-1)=x²
57*99+44*99=99*(44+57)=99*101=(100-1)(100+1)=100²-1=10000-1=99999x^2+16(x+y)^2-24x(x+y)=[3x-4（x
4x=9yx=9/4*y(1)(x+y)/y=[(9/4)y+y]/y=(9/4+1)y/y=9/4+1=13/4(2)(y-x)/2x=[y-(9/4)y]/[2*(9/4)y]=(1-9/4)y/
16(x-y)²-9(x+y)²=(4x-4y)²-(3x+3y)²=(4x-4y+3x+3y)(4x-4y-3x-3y)=(7x-y)(x-7y)
16(x-y)²+24(y²-x²)+9(x+y)²=[4(x-y)]²+2*4(x-y)*3(x+y)+[3(x+y)]²=[4(x-y)
16(x-y)²-9(x+y)²=【4（x-y）+3(x+y)】【4(x-y)-3(x+y)】=(7x-y)(x-7y)在我回答的右上角点击【评价】,然后就可以选择【满意,问题已经
完整设1/(x+y)=a,1/(x-y)=b原方程组可变为4a+6b=39b-a=1a=9b-136b-4+6b=3b=1/6,a=1/2x+y=2x-y=6所以原方程组的解为：x=4,y=-2
55分钟前四个肯定发生|二级x-y）²-x+yx²+四分之一y²-xya²-6a（b-c）+9（b-c）²2x²-10x-12已知x-5y=
判断X的数值是否大于Y的数值如果是则为真等式去X的值反之取Y的值
16(X+Y)平方-9(Y-X)平方=[4(x+y)]²-[3(y-x)]²=[4x+4y-3y+3x][4x+4y+3y-3x]=(7x+y)(x+7y)
16(x-y)^2-9(x+y)^2=(4x-4y)²-(3x+3y)²=(4x-4y+3x+3y)(4x-4y-3x-3y)=(7x-y)(x-7y)