3x-4/5=1/5（2/5+3/4）-x=11/20x-2/11-9/11=3又7/12

1x+2x+3x+4x+5x+6x+7x+8x+9x+10x+11x+12x+13x+14x+15x=550 （1） x-3/x-2 - x-5/x-4=x-7/x-6 - x-9/x-8 x+2x+3x+4x+5x+6x+7x+8x+9x=9x-8x-7x-6x-5x-4x-3x-2x-x.x等于多少? (3x-2y)(4x-5y)-11(x+y)(x-y)+5xy,已知X=3又1/2,y=2又1/3 x^5+x^4 = (x^3-x)(x^2+x+1)+x^2+x (2x-1)/(x-1)(x-2)=(x-5)/(x-2)(x-3) x/2x^2-11x-21=(x+7)/x^2-1 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), -6x+3=2x+11 x=3/2x+14 3/4x-6=3/2x+3 20-3x=7x+4 5/9x+2=1/3x+4 7/2—x=5/1 x—12/5=1 x+1又分之4/1=5/1 x—20/11=4/3 x除2.5=6.25 x—0. 1+2x+3x^2+4x^3+5x^4+6x^5+7x^6+8x^7+9x^8+10x^9+11x^10当x=-1时的值 x的平方-2x+1=15 ; x(2x-5)=4x-10 ; x的平方+5x+7=3x=11