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D( a )
a-17 = 0
a+8 = 0
a-17 = 0
a-17 = 0
a-17 = 0 // + 17
a = 17
a+8 = 0
a+8 = 0
a+8 = 0 // - 8
a = -8
a in (-oo:-8) U (-8:17) U (17:+oo)
(-4*a)/(a+8) = 12/(a-17) // - 12/(a-17)
(-4*a)/(a+8)-(12/(a-17)) = 0
(-4*a)/(a+8)-12*(a-17)^-1 = 0
(-4*a)/(a+8)-12/(a-17) = 0
(-4*a*(a-17))/((a+8)*(a-17))+(-12*(a+8))/((a+8)*(a-17)) = 0
-4*a*(a-17)-12*(a+8) = 0
56*a-4*a^2-96 = 0
56*a-4*a^2-96 = 0
4*(14*a-a^2-24) = 0
14*a-a^2-24 = 0
DELTA = 14^2-(-24*(-1)*4)
DELTA = 100
DELTA > 0
a = (100^(1/2)-14)/(-1*2) or a = (-100^(1/2)-14)/(-1*2)
a = 2 or a = 12
4*(a-2)*(a-12) = 0
(4*(a-2)*(a-12))/((a+8)*(a-17)) = 0
(4*(a-2)*(a-12))/((a+8)*(a-17)) = 0 // * (a+8)*(a-17)
4*(a-2)*(a-12) = 0
( a-12 )
a-12 = 0 // + 12
a = 12
( a-2 )
a-2 = 0 // + 2
a = 2
a in { 12, 2 }
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