（2x+1)(2x-1)+3(x-2)(x-z)=(7x+1

matlab函数绘制f(x)=(x^3-7x+e^x)/(x^3-x),x[-4,4]和z=4/（1+x^2+y^2) x^5+x^4 = (x^3-x)(x^2+x+1)+x^2+x {5x-3y+z=2{5x+2y-4z=3{-5x+y-z=2 {x-y-z=-1{3x+5y+7z{4x-y+2x=- 有这样一道题 计算(x^2-2x+1)/(x^3-x)除以(x-z)/(x^2+x) 已知 x,y,z都是正实数,且 x+y+z=xyz 证明 (y+x)/z+(y+z)/x+(z+x)/y≥2(1/x+1 已知x/2=y/3=z/4,求下列各式 （1）(x+y+z)/x (2)(x-y+2x/(x-y-2z) |X-1|+|X-2|+|X-3|+|X-4|+|X-5|+|X-6|+|X-7|+|X-8|+|X-9|+|X-10| x+2y-z=1 3x-3y+z=2 3x+3y+z=7 x:y=1:2 z:x=3:1 x +y+z=12 x+2y=3 x+y+z=36 2x+y+z=15 2y=3z x-y=1 x+2y+z x-z=-1 2x+z-y=1 x-y-z=-1 3x+5y+7z=11 4x-y+2z=-1 分别求出x=?y=?z=? (2x-1)/(x-1)(x-2)=(x-5)/(x-2)(x-3) x/2x^2-11x-21=(x+7)/x^2-1