(-2x)*(x2-5x+6)-4x(2x2-3x+1)

(x2+3x+9)/(x2-27)+(6x)/(9x-x2)-(x-1)/(6+2x) 1/(x2+3x+2)+1/(x2+5x+6)+1/(x2+7x+12)=1/(x+4) 解方程：1/x2+x +1/x2+3x+2 +1/x2+5x+6 +1/x2+7x+12 +1/x2+9x+20=5/x 化简计算~1/(x2-5x+6) - 1/(4x-x2-3) - 1/(3x-x2-2) 1/(x2+x)+1/(x2+3x+2)+1/(x2+5x+6)+1/(x2+7x+12)=4/21 (x-2)(x2-6x-9)-x(x-5)(x-3)其中x= -1/3 5x2—[x2+(4x—x2)—2(x2—3x)] 解分式方程:2/x2+5x+6 + 3/x2+x-6=4/x2-4 5x2+4-3x2-5x-2x2-5+6x． x2+3x+9/x2-27+6x/9x-x2-x-1/6+2x 化简 化简x2+3x+9/x2-27+6x/9x-x2-x-1/6+2x 解方程x-4/x2+x-2=1/(x-1)+(x-6)/(x2-4)