400-(x+150)/400+100-(2x+150)=75%
y=3(2x*150*12/x*400)=900(x+16/x)
400=x^2+(x+x)^2
(20-2x)(20-2x)x>400 x=?
(X+X)+(X-X)+(X*X)+(X/X)=100
x^2+5x-150=0,求X
2x+5X(39-x)=150
2x+3x+4x+5x+x+6x+7x=100
150-x/x*100%=25%
2*【x+(x+40)】=400
解方程:25%x=75 60%x-35%x=125 x-40%x=120 x+15%x=115 15x-30=150 8
(40-x)(20+2x)=1200 800+80X-20X-2x^2=1200 -2x^2+60X-400=0 x^2
1X+2X+3X…+98X+99X+100X=50500X X等于多少?