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D( x )
1-(4*x) = 0
1-(4*x) = 0
1-(4*x) = 0
1-4*x = 0
1-4*x = 0 // - 1
-4*x = -1 // : -4
x = -1/(-4)
x = 1/4
x in (-oo:1/4) U (1/4:+oo)
(11-(2*x))/(1-(4*x)) = 1.2 // - 1.2
(11-(2*x))/(1-(4*x))-1.2 = 0
(11-2*x)/(1-4*x)-1.2 = 0
(11-2*x)/(1-4*x)+(-1.2*(1-4*x))/(1-4*x) = 0
11-1.2*(1-4*x)-2*x = 0
2.8*x+9.8 = 0
(2.8*x+9.8)/(1-4*x) = 0
(2.8*x+9.8)/(1-4*x) = 0 // * 1-4*x
2.8*x+9.8 = 0
2.8*x+9.8 = 0 // - 9.8
2.8*x = -9.8 // : 2.8
x = -9.8/2.8
x = -3.5
x = -3.5
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