已知x加y等于五xy等于
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X+Y=5,XY=2,5X+4Y-3X-2Y+XY=2X+2Y+XY=2(X+Y)+XY=2×5+2=12.
(2X-3Y-2XY)-(X-4Y+XY)=2X-3Y-2XY-X+4Y-XY=X+Y-3XY因为x加y等于110,xy等于33所以原式等于:110-33*3=11
x+y=8x²+2xy+y²=64xy=122xy=24x²+y²=40
X²+Y²=10..(1)X+Y=6..(2)(2)²-(1)得2XY=26XY=13如果认为讲解不够清楚,
(3x+5xy-3y)/(2y-7xy-2x)=(3/y+5-3/x)/(2/x-7-2/y)=[5-3(1/x-1/y)]/[2(1/x-1/y)-7]=(5-15)/(10-7)=-10/3
X²+y²-2x+4y+5=0(x²-2x+1)+(y²+4y+4)=0(x-1)²+(y+2)²=0∴{x-1=0y+2=0∴x=1,y=
x等于0y等于2.5xy等于0..
已知x平方加xy等于8,y平方加xy等于9,则x平方加y平方加2xy值是8+9=17
x+y=7y=7-xxy=x(7-x)=12x=3或4x=3,y=4或x=4,y=3x-y=1或-1
由已知得x+y=10,xy=25-24=1,所以3x^2-5xy+3y^2=3(x+y)^2-11xy=300-11=289.
x=5-2√6,y=5+2√6x+y=(5-2√6)+(5+2√6)=10xy=(5-2√6)(5+2√6)=5²-(2√6)²=13x²-5xy+3y²=3(
x^2-y^2=x^2+2xy+y^2-4xy=(x+y)^2-4xy=5^2-4×3=25-12=13
由题可知x=-3,y=-5,x+y=-8,
x^2减6xy加9y等于0.则x:y等于_3:1___.
(x+y)^2=x∧2+y∧2+2xy=9x∧2+y∧2=9-2×(-9)=27
x/y+y/x=(x²+y²)/xyx²+y²=(x+y)²-2xy=36-16=20原式=20/8=2.5
xy分之【x加y】等于2分之一xy=2(x+y)【xy加x加y】分之xy=2(x+y)/[2(x+y)+x+y]=2(x+y)/[3(x+y)]=2/3
根据(x+y)2=x2+y2+2xy,可得x2+y2=13