30÷（1+1/3)x-15÷x=5

x^5+x^4 = (x^3-x)(x^2+x+1)+x^2+x 1x+2x+3x+4x+5x+6x+7x+8x+9x+10x+11x+12x+13x+14x+15x=550 5x十2x=42 15十2x一3=48 2x十3x十17=37 6x一3x=6÷5 9x一2x=1 (（x²-5x+6)/(12-7x+x²))²÷((x²+3x+2)/(x
x(2-1/x)+x/(x^2-2x)÷(3-x)/(x^2-4) 解方程x/(x-2)=2x/(x-3)+(1-x)/(x-5x+6) (x+1-1/1-x)÷(x-x²/x-1) (x-4/x-x-6+ x+2/x-3)÷x+1/x-3 已知3x*x-x=1,求6x*x*x+7x*x-5x+2000 已知x²+3x-1=0 求（x-3）÷（3x²-6x）÷(x+2-[5÷(x-2)])的值 先化简代数式再求值(3/x+1 - x+1)÷x²-2x/x+1,其中x满足方程x/x-1+1/x=1 先化简,再求值:x^2-5x+6/3x^2-3x÷(1-3/x+1)(1+2/x-3),其中x=2. 先化解,在求值;(3x/x-1-x/x+1)÷x四次方-4x²/x³-x,其中x=根号2+2