(x+15)*6.2/2-(15-x)*6.2/2=18.

x(x*x-6x-9)-x(x*x-8x-15)+2x(3-x) 通分:x+4/x^2-8x+15,x-5/x^2+x-12,x-3/x^2-x-20 X(x平方-6x-9)-x(x平方-8x-15)+2x(3-x)其中x=-六分之一 计算:[(x+2)/(x+3) - (x+1)/(x+2) + (x+4)/(x+5) - (x+3)/(x+4) / (x^2 + 7x + 13)/(x^2 + 8x + 15) [(x+2)/(x+3)-(x+1)/(x+2)+(x+4)/(x+5)-(x+3)/(x+4)]/[(x的平方+7x+13)/(x的平方+8x+15)] 2x(x-1)-x(2x-5)=15 因式分解 (x+1)(x+2)(x+5)(x+7)+15 （x+1)(x+2)(x+5)(x+7)+15 因式分解 因式分解1+x+x^2+x^3+```+x^15 (x+1)(x+2)(x+3)(x+4)-15 x²-2x-15 (x^21+x^15+x^12+x^9+x^6+x^3+1)/(x^2+x+1) x^3+x-30(分解因式);x^12-y^12;x^15+x^14+x^13.x^2+x+1 x/x²-8x+15≥2x/(x²-8x+15)≥2 (x^2+x-1)-4x^2-4x+7-2x^2+15x-7 数学题x-15/x^2-9-2x/9-x^2÷x/3+x 解方程(x-3/x)-(3-x/x+1)=5x-15/2x+2 15X(4X-8)-5X(2X+10)=6X(5X-20)