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x in (-oo:+oo)
(2/7)*(x-4)^2-1 = 0
2/7*(x-4)^2-1 = 0
2/7*(x-4)^2-1 = 0
2/7*x^2-16/7*x+25/7 = 0
2/7*x^2-16/7*x+25/7 = 0
1/7*(2*x^2-16*x+25) = 0
2*x^2-16*x+25 = 0
DELTA = (-16)^2-(2*4*25)
DELTA = 56
DELTA > 0
x = (56^(1/2)+16)/(2*2) or x = (16-56^(1/2))/(2*2)
x = (2*14^(1/2)+16)/4 or x = (16-2*14^(1/2))/4
1/7*(x-((16-2*14^(1/2))/4))*(x-((2*14^(1/2)+16)/4)) = 0
1/7*(x-((16-2*14^(1/2))/4))*(x-((2*14^(1/2)+16)/4)) = 0
( 1/7 )
1/7 = 0
x belongs to the empty set
( x-((16-2*14^(1/2))/4) )
x-((16-2*14^(1/2))/4) = 0 // + (16-2*14^(1/2))/4
x = (16-2*14^(1/2))/4
( x-((2*14^(1/2)+16)/4) )
x-((2*14^(1/2)+16)/4) = 0 // + (2*14^(1/2)+16)/4
x = (2*14^(1/2)+16)/4
x in { (16-2*14^(1/2))/4, (2*14^(1/2)+16)/4 }
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