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x in (-oo:+oo)
y = x*((900-(3*x))/4) // - x*((900-(3*x))/4)
y-(x*((900-(3*x))/4)) = 0
y-(x*((900-3*x)/4)) = 0
(-1*x*(900-3*x))/4+y = 0
(-1*x*(900-3*x))/4+(4*y)/4 = 0
4*y-1*x*(900-3*x) = 0
3*x^2-900*x+4*y = 0
(3*x^2-900*x+4*y)/4 = 0
(3*x^2-900*x+4*y)/4 = 0 // * 4
3*x^2-900*x+4*y = 0
3*x^2-900*x+4*y = 0
DELTA = (-900)^2-(3*4*4*y)
DELTA = 810000-48*y
810000-48*y = 0
810000-48*y = 0 // - 810000
-48*y = -810000 // : -48
y = -810000/(-48)
y = 16875
DELTA = 0 <=> t_3 = 16875
x = 900/(2*3) i y = 16875
x = 150 i y = 16875
( x = ((810000-48*y)^(1/2)+900)/(2*3) or x = (900-(810000-48*y)^(1/2))/(2*3) ) i y > 16875
( x = ((810000-48*y)^(1/2)+900)/6 or x = (900-(810000-48*y)^(1/2))/6 ) i y > 16875
y-16875 > 0
y-16875 > 0 // + 16875
y > 16875
x in { 150, ((810000-48*y)^(1/2)+900)/6, (900-(810000-48*y)^(1/2))/6 }
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