7X-3y=-1 6X-5y=1
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原式=(9x²+24xy+16y²-4x²+y²-5x²+6xy-y²)÷(-2y)=(30xy+16y²)÷(-2y)=-15x
x-y/7-x+y/10=1/2两边乘7010x-10y-7x-7y=353x-17y=35(1)2(x-y)+5(x+y)=32x-2y+5x+5y=37x+3y=3(2)(2)*3-(1)*79y
3(x+y)+3(y-x)=1(1)3(x+y)+4(y-x)=-1(2)(2)-(1)得y-x=-2(3)代入(1)3(x+y)-6=1x+y=7/3=>x=7/3-y又由(3)得x=y+2y+2=
再问:其他呢?再答:等等。这个是方法,要不要自己尝试下?
因为(x-y)/(x+y)=3,则(x+y)/(x-y)=1/3则5(x-y)(x+y)-(x+y)/2(x-y)=5*3-1/(3*2)=15-1/6=89/6
x-y=1,x+y=-73(x+y)+20(x-y)-5=3×(-7)+20×1-5=-21+20-5=-6
(2x+(y-1))(2x-(y-1))=4x^2-(y-1)^2(3x+y)(3x-y)=9x^2-y^2相减得4x^2-y^2+2y-1-9x^2+y^2=-5x^2+2y-1带入得-5*1/25
5(X-3Y)-6=2X+1,5x-15y-6=2x+13x-15y=7(1)3(X+Y)=4(2X-Y)+163x+3y=8x-4y+165x-7y=-16(2)(1)×5-(2)×3得15x-75
最后一个一次函数的x前面系数绝对值越大越靠近y轴
7y(x-3y)²-2(3y-x)³=7y(3y-x)²-2(3y-x)³=(3y-x)²[7y-2(3y-x)]=(3y-x)²(7y-6
解方程组得到{x=16/7y=3/7∴7y(x-3y)=3×(16/7-9/7)=3
解(x-y)(x+y)-(x-2y)²+x(3x-5y)-(x-y)(x-2y)=(x²-y²)-(x²-4xy+4y²)+(3x²-5xy
只需要把方程加减消元就可以咯
x(x*x-1)+x(5-x*x)-6y+7=-x+5x-6y+7=2(2x-3y)+7=2*(-4)+7=-8+7=-1再问:能在写详一点吗-x+5x-6y+7再答:x(x*x-1)+x(5-x*x
画出限定区域如图z=(x+y)/x =1+y/xy/x=(y-0)/(x-0)看成区域点与原点连线的斜率显然在A(1,2)斜率有最大值=2在(2,1)斜率有最小值=1/2∴z最大值=2+1=
先将第一条式子移项得到7x-5x+x=3y/5+y/2-y/3(右边通分)得到x=23y/90(1)第二式子两边同乘以15得到15x=15y+8(2)把(1)代入(2)中得到的结果自己算啊!
展开x^2-2y^2-xy=-5x^2-2y^2+xy=7所以x^2-2y^2=1xy=6上式除以下式,解分式方程x/y=3/2或-4/3(舍去)所以x^2=9y^2=4x=3y=2或x=-3y=-2
x+y=3则y=3-x带入x+2y=9解得x=-3,y=6剩下的都这样解
原式=x-x+x-x+……-x+(2-1+4-3+5-4+……+2008-2007-2009)y=0+(1×1004-2009)y=-1005y=1005/2