x2-3xy-10y2 x 9y-2因式分解
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x2-xy=-3①,2xy-y2=-8②,①×2+②×3得:2x2-2xy+6xy-3y2=-6-24=-30,则2x2+4xy-3y2=-30.
∵2(x2+xy)-3(xy+y2)=2x2-xy-3y2,∴2x2-xy-3y2=2×3-3×(-2)=12.故选A.
∵x2+xy=-3,xy+y2=7,∴(x2+xy)+(xy+y2)=-3+7=4,即x2+2xy+y2=4.
3xy(x²y-xy²+xy)-xy²(2x²-3xy+2x)=3x³y²-3x²y³+3x²y²-
A=-6-4+2+1=-7,B=6+4-2+1=9A-2B=-7-2x9=-25
有x2+xy=3可得,2x2+2xy=6 (1),有xy+y2=-2得,3xy+3y2=-6 (2),根据分析,(1)-(2)可得,2x2-xy-3y2=6-(-6)=
十字相乘法原式=(2x-3y)(x+y)
原式=(2x²-3xy+4y²)+(x²+2xy-3y²)=(2x²+x²)+(-3xy+2xy)+(4y²-3y²)=
x2+2xy-3y2=x2-xy+3xy-3y2=x2-xy+3(xy-y2),∵x2-xy=3,xy-y2=-5,∴x2+2xy-3y2=3+3×(-5)=-12.
x2-4xy+3y2=0因式分解(x-3y)(x-y)=0所以x=3y或者x=y带入第二个式子得到两组解x=3,y=1或者x=y=根号下5
答:x²+y²=10xy=3,y=3/x代入上式得:x²+(3/x)²=10整理得:(x²)²-10*x²+9=0(x²
6x2-xy-15y2=(2x+3y)(3x-5y)=0,所以x=-3/2y或x=5/3y
x2y2+3xy+2=(xy)^2+3xy+2=(xy+2)(xy+1)很高兴能帮助您~!
=[x+(3-√5)/2*y][x-(3-√5)/2*y]有点牵强,但这是唯一的答案了
2x²-xy-3y²=2x²+2xy-3xy-3y²=2(x²+xy)-3(xy+y²)已知x²+xy=3,xy+y²=
原式=12xy+3x2-5xy-6xy-4x2,=xy-x2.
0.X^2+XY=3;(1)XY+Y^2=2;(2)2*(1)-3*(2)=2*X^2-XY-3*Y^2=2*3-3*2=0
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
原式=2x2-2xy-6x2+9xy-2x2+2x2-xy+y2=-2x2+5xy+2y2,当x=-1,y=-2时,原式=-2+10+8=16.