7.8x-x+13=39 0.75/x=1.15/2
X-35%X=7.8 X+160%X=39
(X+X)+(X-X)+(X*X)+(X/X)=100
x+x+2x+2x+3x+4x=39
解方程((13x-x^2)/(x+1))(x+(13-x)/(x+1))=42
(13x-x^2)/(x+1)[x+(13-x)/(x+1)]=42
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
已知 X=4- 根号3 求 (X*X*X*X-6X*X*X-2X*X+18X+23) / (X*X-8X+15)的值
x/x平方-x+2=2x/x+1
x+2x+3x+4x+5x+6x+7x+8x+9x=9x-8x-7x-6x-5x-4x-3x-2x-x.x等于多少?
若x=π/3,|x+1|+|x+3|+...+|x+13|-|x+2|-|x+4|-...-|x+12|
先化简,再求值:(x-2/x-x+2/x)/x-2/4x,x=2011