x+2/5x=9/20

x+2x+3x+4x+5x+6x+7x+8x+9x=9x-8x-7x-6x-5x-4x-3x-2x-x.x等于多少? x+2/5x=9/20 计算:(1/X^2+3X+2)+(1/X^2+5X+6)+(1/X^2+7X+12)=(1/X^2+9X+20) y=(x-1)(x-2)(x-3)(x-4)(x-5)(x-6)(x-7)(x-8)(x-9)(x-10)的导数在x=1 设函数f(x)=(x-1)(x-2)(x-3)(x-4)(x-5)(x-6)(x-7)(x-8)(x-9)(x-10), 解方程:(x+3)/(x+2)-(x+5)/(x+4)=(x+7)/(x+6)-(x+9)/(x+8) （1） x-3/x-2 - x-5/x-4=x-7/x-6 - x-9/x-8 (4x+2)/x+(4x-22)/(x-5)=(x-6)/(x-4)+(7x+9)/(x+1) 解方程（x-2）X（x的平方-6x-9）=x(x-5)X(x-3) 解方程：(x-2)(x^2-6x-9)=x(x-5)(x-3) (x-2)(x2-6x-9)-x(x-5)(x-3)其中x= -1/3 解方程5题3x+7x=9x+84x-3（20-x)=6x-7(11-x)2x+(x-1/3)=1-(x-2/5)3x+2