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D( x )
12-(8*x^2)-(20*x) = 0
12-(8*x^2)-(20*x) = 0
12-(8*x^2)-(20*x) = 0
12-8*x^2-20*x = 0
12-8*x^2-20*x = 0
DELTA = (-20)^2-(-8*4*12)
DELTA = 784
DELTA > 0
x = (784^(1/2)+20)/(-8*2) or x = (20-784^(1/2))/(-8*2)
x = -3 or x = 1/2
x in (-oo:-3) U (-3:1/2) U (1/2:+oo)
(8*x^2-(40*x)+48)/(12-(8*x^2)-(20*x)) = 0
(8*x^2-40*x+48)/(12-8*x^2-20*x) = 0
8*x^2-40*x+48 = 0
8*(x^2-5*x+6) = 0
x^2-5*x+6 = 0
DELTA = (-5)^2-(1*4*6)
DELTA = 1
DELTA > 0
x = (1^(1/2)+5)/(1*2) or x = (5-1^(1/2))/(1*2)
x = 3 or x = 2
8*(x-2)*(x-3) = 0
12-8*x^2-20*x = 0
4*(3-2*x^2-5*x) = 0
3-2*x^2-5*x = 0
DELTA = (-5)^2-(-2*3*4)
DELTA = 49
DELTA > 0
x = (49^(1/2)+5)/(-2*2) or x = (5-49^(1/2))/(-2*2)
x = -3 or x = 1/2
4*(x+3)*(x-1/2) = 0
(8*(x-2)*(x-3))/(4*(x+3)*(x-1/2)) = 0
( x-2 )
x-2 = 0 // + 2
x = 2
( x-3 )
x-3 = 0 // + 3
x = 3
x in { 2, 3 }
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