0.4X=X-50

（X+X)+(X-X)+(X*X)+(X/X)=100 X-0.4X=36 0.2x+0.4x=12 x=?20x+x=420 x=? x+x=x+15 130%x+x=4.6 x÷50%=10 x/9-x/15=16% 用递归法求y=x-(x*x*x/3!)+(x*x*x*x*x/5!)-(x*x*x*x*x*x*x/7!)+. 2X- 30X+5 /0.2=0.4- 50X-2 /5 方程x-0.4x+360:x=3: 0.4x+3.2=2.5x+0.05 X是多少 90/(x-90)=(2x-50)/(x+50) 3x=x+100 x=50 x-1)(X-2)(x-3)...(x-50)+x(x-2)(X-3)...(X-50)+...+x(x-1)(x-2)