(1+30%)X×80%=200+X

(1+30%)X×80%=200+X 80%x+30-x=10%x x*(1+30%)*80%-x=112 [x(1+30%)80%]-x=2700 x(30-x)=200 x/6+x/12+x/20+x/30=1 X(X-1)=X (x+30)*(x-18)=x*x 计算：(x+1)x=7 (x-1)(x+2)=30 (3-x)(3-x)+x=9 x-2/5x-(x-2/5x)2/3-(2/5x-1/3x)=30求x (x^2-3x+1) (x^2+3x+2)( x^2-9x+20)= -30求X (40-x)(20+2x)=1200 800+80X-20X-2x^2=1200 -2x^2+60X-400=0 x^2-30X+200=0 (X-10)(X-20)=0 X-10=0 X-20=0(X-10)(X-20)=0 40-x)(20+2x)=1200 800+80X-20X-2x^2=1200 -2x^2+60X-400=0 ^2-30X+200=0 (X-10)(X-20)=0 x>=1,x x/x-2+x-9/x-7=x+1/x-1+x-8/x-6, x/x-2+x-9/x-7=x+1/x-1+x-8/x-6, 3x*x=1600+x*x-80x x*x*x*x+2008x*x+2007x+2008(提示：x*x*x-1=（x-1）*（x*x+x+1）） x/x平方-x+2=2x/x+1