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a in (-oo:+oo)
a*((16-(2*a))/4)+a*((3*a+21)/5) = 10/9-a // - 10/9-a
a*((16-(2*a))/4)+a*((3*a+21)/5)+a-(10/9) = 0
a*((16-2*a)/4)+a*((3*a+21)/5)+a-10/9 = 0
(a*(16-2*a))/4+(a*(3*a+21))/5+a-10/9 = 0
(5*9*a*(16-2*a))/(4*5*9)+(4*9*a*(3*a+21))/(4*5*9)+(4*5*9*a)/(4*5*9)+(-10*4*5)/(4*5*9) = 0
5*9*a*(16-2*a)+4*9*a*(3*a+21)+4*5*9*a-10*4*5 = 0
18*a^2+1476*a+180*a-200 = 0
18*a^2+1656*a-200 = 0
18*a^2+1656*a-200 = 0
2*(9*a^2+828*a-100) = 0
9*a^2+828*a-100 = 0
DELTA = 828^2-(-100*4*9)
DELTA = 689184
DELTA > 0
a = (689184^(1/2)-828)/(2*9) or a = (-689184^(1/2)-828)/(2*9)
a = (12*4786^(1/2)-828)/18 or a = (-12*4786^(1/2)-828)/18
2*(a-((-12*4786^(1/2)-828)/18))*(a-((12*4786^(1/2)-828)/18)) = 0
(2*(a-((-12*4786^(1/2)-828)/18))*(a-((12*4786^(1/2)-828)/18)))/(4*5*9) = 0
(2*(a-((-12*4786^(1/2)-828)/18))*(a-((12*4786^(1/2)-828)/18)))/(4*5*9) = 0 // * 4*5*9
2*(a-((-12*4786^(1/2)-828)/18))*(a-((12*4786^(1/2)-828)/18)) = 0
( a-((-12*4786^(1/2)-828)/18) )
a-((-12*4786^(1/2)-828)/18) = 0 // + (-12*4786^(1/2)-828)/18
a = (-12*4786^(1/2)-828)/18
( a-((12*4786^(1/2)-828)/18) )
a-((12*4786^(1/2)-828)/18) = 0 // + (12*4786^(1/2)-828)/18
a = (12*4786^(1/2)-828)/18
a in { (-12*4786^(1/2)-828)/18, (12*4786^(1/2)-828)/18 }
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