已知y=1y=xy=x2是某二阶非齐次线性微分方程的三个解,
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![已知y=1y=xy=x2是某二阶非齐次线性微分方程的三个解,](/uploads/image/f/4230986-50-6.jpg?t=%E5%B7%B2%E7%9F%A5y%3D1y%3Dxy%3Dx2%E6%98%AF%E6%9F%90%E4%BA%8C%E9%98%B6%E9%9D%9E%E9%BD%90%E6%AC%A1%E7%BA%BF%E6%80%A7%E5%BE%AE%E5%88%86%E6%96%B9%E7%A8%8B%E7%9A%84%E4%B8%89%E4%B8%AA%E8%A7%A3%2C)
(x2+y2)/(x-y)=(x2+y2-2xy+2xy)/(x-y)因为xy=1,所以=[(x-y)^2+2]/(x-y)=(x-y)+2/(x-y)因为x>y>0所以(x-y)>0所以有不等式的定
x-y=1,(x-y)^2=x^2+y^2-2xy=12xy=25-1=24,xy=12(x+y)^2=x^2+y^2+2xy=25+24=49x^2-xy+y^2=25-12=13
∵x²-2xy-3y²=0∴*(x-3y)(x+y)=0∴x=3y或x=-y(1)2x+y/x-2y当x=3y时,原式=7y/y=7当x=-y时,原式=y/(-3y)=-1/3(2
x-2y=12,两边平方得,x2+4y2-4xy=144,移项得,x2+4y2-1=4xy+143,将xy=-25代入上式得,x2+4y2-1=43.答:x2+4y2-1的值是:43.
x2+y2+3xy=(x+y)2+xy,∵x+y=4,xy=2,∴x2+y2+3xy=42+2=18.故答案为18.
x²+(2-y)x+y²-y+1=0方程有解的条件是:△=b²-4ac≥0→-3y²≥0∴y=0∴x=-1
(1)A-2B=2x2+3xy+2y-1-2(x2−xy+x−12)=2x2+3xy+2y-1-2x2+2xy-2x+1=5xy+2y-2x,当x=y=-2时,A-2B=5xy+2y-2x=5×(-2
解题思路:完全平方公式解题过程:varSWOC={};SWOC.tip=false;try{SWOCX2.OpenFile("http://dayi.prcedu.com/include/readq.
∵x+y=4,xy=2,∴x2+y2+3xy,=(x+y)2+xy,=42+2,=18.
x^2+(2-y)x+y^2-y+1=0这个关于x的二次方程有解b^2-4ac>0-3y^2>0所以y=0x=-1
X2次方+Y2次方=(X+Y)^2-2XY=7^2-2*2=45再问:这个^是什么再答:x^2表示x的2次方
因为x2+y2=5,xy=2所以(x+y)^2=9x+y=+/-3所以1/(1/x+1/y)=xy/(x+y)=+/-2/3
∵2x2+xy-3y2=0(y≠0),即(2x+3y)(x-y)=0,∴2x+3y=0,x-y=0,解得:x=-32y,x=y,当x=-32y时,xy=-32;当x=y时,xy=1.
(1)∵A=2x2+3xy+2y-1,B=x2-xy+x-12,x-y=-1,xy=1,∴A-2B=(2x2+3xy+2y-1)-2(x2-xy+x-12)=2x2+3xy+2y-1-2x2+2xy-
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2x²-xy-3y²=2x²+2xy-3xy-3y²=2(x²+xy)-3(xy+y²)已知x²+xy=3,xy+y²=
X2+2XY+Y2=(x+y)²=1;
由x2+xy+y2=3得,x^2+y^2=3-xyx^2+y^2≥2xy得,xy≤1所以x^2-xy+y^2=3-2xy≥1等号成立当且仅当x=y=±1
因为x²+4y²+x²y²-6xy+1=0(x²-4xy+4y²)+(x²y²-2xy+1)=0(x-2y)²