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x in (-oo:+oo)
y = (x/4)*(x-8) // - (x/4)*(x-8)
y-((x/4)*(x-8)) = 0
y-1*1/4*x*(x-8) = 0
y-1*1/4*x*(x-8) = 0
2*x-1/4*x^2+y = 0
2*x-1/4*x^2+y = 0
2*x-1/4*x^2+y = 0
DELTA = 2^2-(-1/4*4*y)
DELTA = y+4
y+4 = 0
y+4 = 0 // - 4
y = -4
DELTA = 0 <=> t_3 = -4
x = -2/(-1/4*2) i y = -4
x = 4 i y = -4
( x = ((y+4)^(1/2)-2)/(-1/4*2) or x = (-(y+4)^(1/2)-2)/(-1/4*2) ) i y > -4
( x = -2*((y+4)^(1/2)-2) or x = 2*((y+4)^(1/2)+2) ) i y > -4
y+4 > 0
y+4 > 0 // - 4
y > -4
x in { 4, -2*((y+4)^(1/2)-2), 2*((y+4)^(1/2)+2) }
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