若方程组3x y=12 2x ay=3的解都是自然数 求出a的值
来源:学生作业帮助网 编辑:作业帮 时间:2024/10/02 19:01:06
由题意得,X=﹣Y①把①代入2x+3y=2k+1得,Y=2K+1②把①代入3X-2Y=4K+3得,﹣5Y=4K+3即Y=﹣4K+3/5③有②③可以得到2K+1=-4K+3/5即10K+5=﹣4K-3解
x^2-2xy-3y^2=0(x-y)^2-4y^2=0(x-y)^2=(2y)^2x-y=±2yx-y=2y或x-y=-2yx1=3yx2=-y将x1,x2分别代入②,得:(3y)^2-y*3y+y
xy/(2x+y)-xy/(2x-y)=3xy/(2x-y)+xy/(2x+y)=4;一、两公式对加得2xy/(2x+y)=7xy=(2x+y)*7/2二、把xy代入原公式求解就行了:(2x+y)*7
(1)x=1.2y=1.4
解1式:(x+4y)(x-y)=0x=-4y时,解2式得:x=-10/3,y=5/6;x=10/3,y=-5/6x=y时,解2式得:x=5,y=5;x=-5,y=-5
x²-2xy+y²=12x²-5xy-3y²=0即(x-y)²=1(2x+y)(x-3y)=02x+y=0或x-3y=0如果2x+y=0,则y=-2x
(2a5)a4=(√2*5+4)a4=(√10+4)a4=√[(√10+4)*4]+4=2(1+√3)+4=6+2√3
(1)×7+(2)×328y+27y=55xy所以y=0或x=1分别代入所以x=0.y=0x=1,y=1/2
xy/3x+2y=1/8,xy/2x+3y=1/73x+2y/xy=8,2x+3y/xy=73/y+2/x=8,2/y+3/x=73/y+2/x=8,2/y+3/x=71/x=1,1/y=2,x=1,
两式相加得x=4+xy即x=4/(1-y)①两式相减得y=-1-4xy②①代入②y=-1-4y*4/(1-y)整理得y²-16y-1=0解得y=8±√65代入①,即可算出x了如有不明白,可以
x+y=-3x=-3-y带入xy=2(-3-y)y=2-y^2-3y-2=0y^2+3y+2=0(y+1)(y+2)=0y1=-1y2=-2x1=-2x2=-1
由题意知,该种群中XAXA=20%、XAXa=10%、XaXa=20%、XAY=10%、XaY=40%,则该种群中XA的基因频率是:(20%×2+10%+10%)÷(20%×2+10%+10%+40%
x2y+xy2=xy*(x+y)因为x+y=-(7+xy)又x+y=(9+2xy)\3所以(9+2xy)\3=-(7+xy)3+2xy\3=-7-xy5xy\3=-10解得xy=-6所以x+y=-(7
x=2,y=0.5
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
x^2+xy=12xy+y^2=4因式分解下,得x(x+y)=12.y(x+y)=4两个方程相加,得(x+y)^2=16所以x+y=±4当x+y=4时,代入x(x+y)=12.y(x+y)=4解得x=
当x=7,y=1{3x-my=16,2x+ny=15即,{21-m=16,14+n=15得,m=5,n=1代入{3(x+y)-m(x-y)=16,2(x+y)+n(x-y)=15,即,{3(x+y)-
因为:xy=(x-10)(y+1)→xy=xy+x-10y-10①xy=(x-15)(y+3)→xy=+3x-15y-45②由①、②得:x=10y+10③x=5y+15④将③‐④得:10y+
由xy+x=16,得x=16/(y+1)代入xy-x=8,得16y/(y+1)-16/(y+1)=8=>16(y-1)/(y+1)=8=>(y-1)/(y+1)=1/2移项,通分得y-3/2(y+1)
由(x-2)(y+3)=xy(x-5)(y+2)=xy得3x-2y-6=02x-5y-10=0上面方程化为6x-4y-12=06x-15y-30=0两式相减得11y=-18,y=-18/11,代入任意