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D( x )
x = 0
2*x = 0
x = 0
x = 0
2*x = 0
2*x = 0
2*x = 0 // : 2
x = 0
x in (-oo:0) U (0:+oo)
(5*x-7)/(2*x) = 4/x // - 4/x
(5*x-7)/(2*x)-(4/x) = 0
(5*x-7)/(2*x)-4*x^-1 = 0
(5*x-7)/(2*x)-4/x = 0
(x*(5*x-7))/(2*x*x)+(-4*2*x)/(2*x*x) = 0
x*(5*x-7)-4*2*x = 0
5*x^2-15*x = 0
5*x^2-15*x = 0
5*x*(x-3) = 0
x-3 = 0 // + 3
x = 3
5*x*(x-3) = 0
(5*x*(x-3))/(2*x*x) = 0
(5*x*(x-3))/(2*x*x) = 0 // * 2*x*x
5*x*(x-3) = 0
( 5*x )
5*x = 0 // : 5
x = 0
( x-3 )
x-3 = 0 // + 3
x = 3
x in { 0}
x = 3
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