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96-((1/3)*(x-15)^2) = 0
(-1/3)*(x-15)^2+96 = 0
96-1/3*(x-15)^2 = 0
96-1/3*(x-15)^2 = 0
10*x-1/3*x^2+21 = 0
10*x-1/3*x^2+21 = 0
10*x-1/3*x^2+21 = 0
DELTA = 10^2-(-1/3*4*21)
DELTA = 128
DELTA > 0
x = (128^(1/2)-10)/(-1/3*2) or x = (-128^(1/2)-10)/(-1/3*2)
x = -3/2*(8*2^(1/2)-10) or x = -3/2*(-8*2^(1/2)-10)
(x+3/2*(8*2^(1/2)-10))*(x+3/2*(-8*2^(1/2)-10)) = 0
(x+3/2*(8*2^(1/2)-10))*(x+3/2*(-8*2^(1/2)-10)) = 0
( x+3/2*(-8*2^(1/2)-10) )
x+3/2*(-8*2^(1/2)-10) = 0 // - 3/2*(-8*2^(1/2)-10)
x = -(3/2*(-8*2^(1/2)-10))
x = -3/2*(-8*2^(1/2)-10)
( x+3/2*(8*2^(1/2)-10) )
x+3/2*(8*2^(1/2)-10) = 0 // - 3/2*(8*2^(1/2)-10)
x = -(3/2*(8*2^(1/2)-10))
x = -3/2*(8*2^(1/2)-10)
x in { -3/2*(-8*2^(1/2)-10), -3/2*(8*2^(1/2)-10) }
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