0.3x+0.2y=1 0.1x+0.5y=1.2 怎么解 要一步步的过程

0.1x+0.3y = 0.15(x+y) 0.1x+0.3y+0.2×300 = 0.18×(x+y+300) x=?y=? 0.1x+0.3y = 0.15(x+y) 0.1x+0.3y+0.2×300 = 0.18×(x+y+300) x=?y=? 解方程组{0.2x+0.3y=-0.1,0.5x+(y/3)=1 解方程组：①4x+3y-5=0,x-2y-4=0.②5x-2=2（y-1）,2（x-2）+（y-1）③0.2x+0.5y=0.2,0.4x+0.1y=0.4④3x-13y=-12,x+3y=2 已知实数x,y满足方程x*x+y*y-4x+1=0.求y-x的最大值 设x.y满足条件y>=0.X-Y+1>=0.x+y-3 x>=1,x-y y=x-1(x 解方程组：（0.2x+0.1y）/2- （4x-y）/10=（x-y）/5+ (3x+0.5y)/30 (3x+2y-1)/8=3-(0.8x-5y)/41=-= 求导 y=[x/(1+x)]^x 0.3x+0.2y=1 解方程组{ 5x+7y=400.3x+0.2y=1解方程组{5x+7y=40 matlab解对数方程组[x,y,z]=solve('0.29744*x/(3+0.1*x+y+z)=(log10((3+x+y+z)/(3+0.1*x+y+z)))^2','0.79*x/(3+0.1*y+z)=(log10((3+x+y+z)/(3+0.1*x+y+z)*(3+y+z)/(3+0.1*y+z)))^2','1.25*x/(3+0.1*z)=(log10((3+x+y+z)/(3+0.1*x+y+z)*(3+y+z)/(3+0.*1y+z)*(3+z)/ 0.2X^2Y-0.5XY^2-0.3X^2Y+0.7X^2Y,当x=-1,y=2/3时,最后=? 0.2x平方y-0.5xy平方-0.3x平方y+o.7x平方y,其中x=-1,y=三分之二 求多项式的值 y'-(1/x)y=xe^-x 0.1x+0.3y=2.5 0.1x-0.1y=2.1,求x,y 合并同类项,3x^2-[7x-(4x-3)-2x^2] 光求值：1/2x-2(x-1/3y^2)+(-3/2x+1/3y^2)其中x=-2,y=2/3 .3y^4-4x^3y+0.2x^2y^2-4y^4+0.5x^3y-1/5x^2y^2其中x=-2,y=0.3 如果x:8=1/y*0.4.x、y不等于0.x：y=( )：( )