(x-1)/(x＾2+3x-2)+6/(2+x-x＾2)-(10-x)/(4-x＾2) =(x-1)/［(x+1)(x+2)］-6/［(x+1)(x-2)］-(x-10)/［(x+2)(x-2)］ =(X^2-3X+2-6X-12-X^2+9X+10)/[(X+2)(X+1)(X-2)] =0