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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
(3.5-x)/x = (y-0.75)/y // - (y-0.75)/y
(3.5-x)/x-((y-0.75)/y) = 0
(3.5-x)/x+(-1*(y-0.75))/y = 0
(y*(3.5-x))/(x*y)+(-1*x*(y-0.75))/(x*y) = 0
y*(3.5-x)-1*x*(y-0.75) = 0
0.75*x+3.5*y-2*x*y = 0
0.75*x+3.5*y-2*x*y = 0
0.75*x+3.5*y = 0 // - 3.5*y
0.75*x = -(3.5*y) // : 0.75
x = (-(3.5*y))/0.75
x = -4.66666667*y
x+4.66666667*y = 0
(x+4.66666667*y)/(x*y) = 0
(x+4.66666667*y)/(x*y) = 0 // * x*y
x+4.66666667*y = 0
x+4.66666667*y = 0 // - 4.66666667*y
x = -(4.66666667*y)
x = -4.66666667*y
x = -4.66666667*y
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