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a in (-oo:+oo)
5-(((3*a)/7)*(3*a-5)) = 0
(-3/7)*a*(3*a-5)+5 = 0
5-3/7*a*(3*a-5) = 0
5-3/7*a*(3*a-5) = 0
15/7*a-9/7*a^2+5 = 0
15/7*a-9/7*a^2+5 = 0
15/7*a-9/7*a^2+5 = 0
DELTA = (15/7)^2-(-9/7*4*5)
DELTA = 1485/49
DELTA > 0
a = ((1485/49)^(1/2)-15/7)/(-9/7*2) or a = (-(1485/49)^(1/2)-15/7)/(-9/7*2)
a = -7/18*((1485/49)^(1/2)-15/7) or a = 7/18*((1485/49)^(1/2)+15/7)
(a+7/18*((1485/49)^(1/2)-15/7))*(a-7/18*((1485/49)^(1/2)+15/7)) = 0
(a+7/18*((1485/49)^(1/2)-15/7))*(a-7/18*((1485/49)^(1/2)+15/7)) = 0
( a+7/18*((1485/49)^(1/2)-15/7) )
a+7/18*((1485/49)^(1/2)-15/7) = 0 // - 7/18*((1485/49)^(1/2)-15/7)
a = -(7/18*((1485/49)^(1/2)-15/7))
a = -7/18*((1485/49)^(1/2)-15/7)
( a-7/18*((1485/49)^(1/2)+15/7) )
a-7/18*((1485/49)^(1/2)+15/7) = 0 // + -7/18*((1485/49)^(1/2)+15/7)
a = -(-7/18*((1485/49)^(1/2)+15/7))
a = 7/18*((1485/49)^(1/2)+15/7)
a in { -7/18*((1485/49)^(1/2)-15/7), 7/18*((1485/49)^(1/2)+15/7) }
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