5x+4x=45

(4/x-5)+(x-3)/(12-x)=(x-45)/(x^2-17x+60) x+2x+3x+4x+5x+6x+7x+8x+9x=9x-8x-7x-6x-5x-4x-3x-2x-x.x等于多少? x-2x+3x-4x+5x.+99x-100x=25求解 2x+3x+4x+5x+x+6x+7x=100 (x-3/x-2)-(x-2/x-1)=(x-5/x4) -(x-4/x-3) x(x+1)+(x+2)+(x+3)+(x+4)+(x+5) = 27求x x-4/x-5 - x-5/x-6=x-7/x-8 - x-8/x-9求x=? 提取公因式:已知x*x-5x+1=0 求x*x*x-4x*x-4x-1 x+2/x+1-x+4/x+3=x+6/x+5-x+8/x+7 x=? 下列式子求导1.f(x)=x^3-3x^2+3x-22.g(x)=-3x^3+5x^2-4x+113.u(x)=-x^3+27x+74.h(x)=42-45x-3x^2+3x^35.f(x)=Lnx+x6.g(x)=x/(2+x^2) 一元二次方程解答!x（5x+4）=5x+44x^2-45=31x-3x^2+22x-24=0(x+8)(x+1)= -12(3x+2)(x+3)=x+14 x^-6x+5=x+4 5*4x+x*x=80 y=|-x.x+4x+5| 写过程x(x-1)+2x(x+1)-3x(2x-5)-x(3x-2)+2x(2-x)=-5x(x-2)-4 5x+4x=45 X一20%X=4 5分之X加上X=60X一20%X=45分之X加上X=60 *-----------------------------------------------*| 6 4 X | 8 X X | X X 5 || X X X | X X X | X 7 8 || X X X | X X X | X X X ||---------------+---------------+--------------- || X X X | X X X | 5 1 X || X X X | X 6 X | X X X || 8 X X | 3 5 X | 2 X X ||