7/9-3x=2/3

x+2x+3x+4x+5x+6x+7x+8x+9x=9x-8x-7x-6x-5x-4x-3x-2x-x.x等于多少? 解方程】(x+8)/(x-3)-(x-9)/(x-4)=(x+7)/(x+8)-(x+2)/(x+3) 解方程：（x-8）/(x-3)-(x-9)/(x-4)=(x+7)/(x+8)-(x+2)/(x+3) 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 x+2/x+3－x+1/x+2=x+8/x+9－x+7/x+8 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 1x+2x+3x+4x+5x+6x+7x+8x+9x+10x+11x+12x+13x+14x+15x=550 a*b=2×a+b 计算x*2x*3x*4x*5x*6x*7x*8x*9x=3039 x= 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