有关y={(x-4)(x-3)/[(x-2)(x-1)]}^1/2求导数的问题.书上两边取对数,得到lny=1/2[ln(x-4)+ln(x-3)-ln(x-2)-ln(x-1)],这里为什么不考虑x＜1的情况?

已知4x=9y求(1)x+y/y (2)y-x/2x有关比例的 y=3x+4/x+1 如何化简成与y=1/x有关的式子y=3x+4/x+1 如何化简成与y=1/x有关的式子 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= x/3=y/4,求(x*x-xy)/(x*x+y*y)的值 （y-x)+x(x-y)^3-(y-x)^4 因式分解 x+3y/y-x,其中x=-4, Matlab的有关东西,将多项式y=x^5+x^4+x^3+x^2+x^1以子程序的方式描述出来. （3x-y)(y+3x)-(4x-3y)（4x+3y)=? {3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1 2（x+y)-3(x-y)=3 ,4(x+y)+3(x-y)=15 （5x+3y)(3y-5x)-(4x-y)(4y+x)= {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 x(x-3y)=4y(x-3y),求x:y 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11