学帮网x+y
来源：学生作业学帮网 编辑：学帮网 时间：2024/05/05 04:16:27
{(x,y)|x|+|y|区域是一个正方形
x>y?x:y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
x^/y-x-y^/y-x化简.原式=(x²-y²)/(y-x)=(x+y)(x-y)/[-(x-y)]=-(x+y)=-x-y亲，能把题目拍下来吗
化简x(y-x)-y(x-y)y^2-x^2你觉得怎么样
y/(x+y)-x/(x-y)y/(x+y)-x/(x-y)=y(x-y)/(x+y)(x-y)-x(x+y)/(x+y)(x-y)=[y(x-y)-x(x+y)]/(x+y)(x-y)=[xy-y^2-x^2-xy]/(x+y)(x-y)
x-y/x-x+y/y-(x+y)(x-y)/y²y/x=2以上错误,修改如下：y/x=2→y=2x(x-y)/x-(x+y)/y-(x+y)(x-y)/y^2=((xy-y^2)-(x^2+xy))/xy-(x^2-y^2)/y
xyx+yyx+yxx+yxy把所有列都加至第一列,第一列都是2x+2y将2x+2y提出,第一列剩下都是1,此时式外边有一因子（2x+2y）用2,3行加第1行负一倍得1yx+y0xy0x-y-x第一列展开得1*（-x^2-y(x-y))=y
(3x-y)(3y+x)-(x-y)(x+y)(3x-y)(3y+x)-(x-y)(x+y)=9xy+3x²-3y²-xy-(x²-y²)=3x²+8xy-3y²-x²+
化简x/y(x+y)-y/x(x+y)x/y(x+y)-y/x(x+y)=x^2/xy(x+y)-y^2/xy(x+y)=x^2-y^2/xy(x+y)=(x+y)(x-y)/xy(x+y)=x-y/xy
化简x/y(x+y)-y/x(x+y)=x^2-y^2为分子,xy(x+y)为分母
化简:(x+y)(x-y)+(x+y)+(x-y)(x+y)(x-y)+(x+y)+(x-y)=(x+y)(x-y)+2xX^2-Y^2+2X（x+y）[(x-y)+(x-y)]x*x-y*y+2x。原式=x2-y2+x+y+x-y=x2+
x+y2*(3x+2y)
(x+y)x＞0,y＞0,a＞0 a(x+y)≤√(x²+y²) a²(x+y)²≤x²+y² (1-a²)(x²+y²)≥2a²xy
|x+y|证明：由|x+y|又已知|2x-y|（1）+（2）得-5/6亦即|y|（注意正负范围值、大于小于是可以直接相加的）可以得出这两个式子-1/3＜x+y＜1/3-1/6＜2x-y＜1/6把x想办法去掉-2/3＜2x+2y＜2/3-1/
xyx+yyx+yxx+yxyc1+c2+c3第2,3列加到第1列2(x+y)yx+y2(x+y)x+yx2(x+y)xyr2-r1,r3-r12(x+y)yx+y0x-y0x-y-x=2(x+y)[-x^2+y(x-y)]=-2(x+y)
化简y(x+y)+(x+y)(x-y)-x^2y(x+y)+(x+y)(x-y)-x^2=(x+y)(y+x-y)-x^2=(x+y)*x-x^2=xy
|x|+|y||x|+|y|
x*x-y*y-(x+y)(x+y),因式分解原式＝(x+y)(x-y)-(x+y)^2=(x+y)(x-y-(x+y))=-2y(x+y)x*x-y*y-(x+y)(x+y)=(x-y)(x+y)-(x+y)(x+y)=(x+y)[(x-
|x+y|似乎要画图这图怎么画求思路充分性：特殊法令x=1.9y=0.01显然不成立必要性：|x+y|
|x|+|y|讨论x,y与0的关系即可,即去掉绝对值：x0,y>0x+y