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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
3/x+2 = (4/5)*x+21/10 // - (4/5)*x+21/10
3/x-((4/5)*x)-(21/10)+2 = 0
(-4/5)*x+3/x-21/10+2 = 0
3*x^-1-4/5*x^1-1/10*x^0 = 0
(3*x^0-4/5*x^2-1/10*x^1)/(x^1) = 0 // * x^2
x^1*(3*x^0-4/5*x^2-1/10*x^1) = 0
x^1
(-4/5)*x^2+(-1/10)*x+3 = 0
(-4/5)*x^2+(-1/10)*x+3 = 0
DELTA = (-1/10)^2-(3*4*(-4/5))
DELTA = 961/100
DELTA > 0
x = ((961/100)^(1/2)-(-1/10))/(2*(-4/5)) or x = (-(-1/10)-(961/100)^(1/2))/(2*(-4/5))
x = -2 or x = 15/8
x in { -2, 15/8}
x in { -2, 15/8 }
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