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x in (-oo:+oo)
x*((200*x-5000)/200) = 0.3 // - 0.3
x*((200*x-5000)/200)-0.3 = 0
(x*(200*x-5000))/200-0.3 = 0
(x*(200*x-5000))/200+(-0.3*200)/200 = 0
x*(200*x-5000)-0.3*200 = 0
200*x^2-5000*x-60 = 0
200*x^2-5000*x-60 = 0
20*(10*x^2-250*x-3) = 0
10*x^2-250*x-3 = 0
DELTA = (-250)^2-(-3*4*10)
DELTA = 62620
DELTA > 0
x = (62620^(1/2)+250)/(2*10) or x = (250-62620^(1/2))/(2*10)
x = (2*15655^(1/2)+250)/20 or x = (250-2*15655^(1/2))/20
20*(x-((250-2*15655^(1/2))/20))*(x-((2*15655^(1/2)+250)/20)) = 0
(20*(x-((250-2*15655^(1/2))/20))*(x-((2*15655^(1/2)+250)/20)))/200 = 0
(20*(x-((250-2*15655^(1/2))/20))*(x-((2*15655^(1/2)+250)/20)))/200 = 0 // * 200
20*(x-((250-2*15655^(1/2))/20))*(x-((2*15655^(1/2)+250)/20)) = 0
( 20 )
20 = 0
x belongs to the empty set
( x-((2*15655^(1/2)+250)/20) )
x-((2*15655^(1/2)+250)/20) = 0 // + (2*15655^(1/2)+250)/20
x = (2*15655^(1/2)+250)/20
( x-((250-2*15655^(1/2))/20) )
x-((250-2*15655^(1/2))/20) = 0 // + (250-2*15655^(1/2))/20
x = (250-2*15655^(1/2))/20
x in { (2*15655^(1/2)+250)/20, (250-2*15655^(1/2))/20 }
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