(10(9-x)+x)-(10x+9-x)=-9

|X-1|+|X-2|+|X-3|+|X-4|+|X-5|+|X-6|+|X-7|+|X-8|+|X-9|+|X-10| 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), (x+7/x+6)+ (x+9/+x+8)=(x+10/x+9)+(x+6/x+5) 1.x+9/x+8- x+10/x+9=x+6/x+5- x+7/x+6； ⒈ 解方程 (X+7)/(X+6)+(X+9)/(X+8)=(X+10)/(X+9)+(X+6)/(X+5) x-4/x-6+x-8/x-10=x-5/x-7+x-7/x-9 1x+2x+3x+4x+5x+6x+7x+8x+9x+10x+11x+12x+13x+14x+15x=550 x*x+2x+x*x+10x+x*x+25+2x+x*x+1+1+16+x*x+4x*x+9-12x+16x*x+4-1 1x()+2x()+3x()+4x()+5x()+6x()+7x()+8x()加9x()+10x()=1980 1X?+2X?+3X?+4X?+5X?+6X?+7X?+8X?+9X?+10X?=1980求?是多少 1/[x(x-1)]+1/[x(x+1)]+…+1/[(x+9)(x+10)]=1/(x+10)