1*X+1*Y=9/80 8*X+10*Y=1怎么解

(x+y+z)÷10=x+1.1 y+x=z-80+y-1 z-y=8x+y+8 x+z÷y=? x+(9-8-y)=10 y+y-(9-8-y)=2 x-y=xx-9.9x xy=11y-1 y=? x=? x+y-xy=?x+(9-8-y)=10y+y-(9-8-y)=2x-y=xx-9.9xxy=11y-1 y=?x=?x+y-xy=? 9y=3x-(x-1),4(x+y)-(2x+4)=8y 已知y/x=9/10则(1-y/x)[x/(y-x)]? 1*X+1*Y=9/80 8*X+10*Y=1怎么解 x+y=5① x=3y+2① 9x-5y=1① 3x-2y=11① x-2y=y+1① 2x-y=7② x+3y=8② 6x-7y=2② 2x+3y=16② 2x-3y=10②3x+2y=y+1①2x-3y=10②D 已知x>0,y>0 x+y+9/x+1/y=10,则x+y则最大值为? 已知正实数x,y满足x+y+1/x+9/y=10,则x+y的最大值是 (x+y)/6+(x-y)/10=1,(x+y)/6-(x-y)/10=5 {6/x+y+10/x-y=30 6/x+y-10/x-y=-1 导数的计算练习题导数的计算（1）y=x^5 （2)y=sinx(3)y=1/x^3(4)y=5^√x(5)y=cosx(6)y=5^x(7)y=log3^x(8)y=lnx(9)f(x)=x^3-x^2-x+1(10)y=2x^3-3x^2+4x-1(11)y=x inx（12）y=xsinx-cosx(13)y=cosx/x(14)y=3x(x^2+2)(15)f(x)=(x-1)^2+3(x-1)(16)f(x)=1 先化简再求值 x(9x-y)-y(y-x)+(x-y)的平方,其中x=-1,y=2 用代入法解下列方程组 ①｛y=1-x 3x+2y=5 ②｛2x-y=5 3x+4y=2 ③｛x-y-3=0 3x-8y=14 ④｛④｛2x-7y=8 3x-8y-10=0⑤｛x=3y+7/2 x=2y+8/3⑥｛3x=5y 4y-3x+9=0急 x=1,y=10,x=2,y=9,x=4,y=8.1,x=8,y=? xy²/(x²y-y) × x²/(x²+x)=(x²-3x)/(x²-5x) × 2x-10/(x²-6x+9)=化简求植x²-1/(x²-x-2)除以x/2x-4,其中x=1/2[x-x/(x+1)]除以[x/(2x-4)] ,其中x=√2+1 （x+y)+(2x+1/1*2y)+(3x+1/2*3y)+.+(9x+1/8*9y) x=2 y=90求和 化简(x+y)+(2x+1/2y)+(3x+2/3y)+(4x+3/4y)+...+(9x+8/9y)=? 已知4x²+y²-4x-6y+10=0求（2/3x（√9x）+(y²√x/y³)×(x²√1/x×5x√y/x)的值