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x in (-oo:+oo)
13/2 = x+(1/2)*x+8 // - x+(1/2)*x+8
13/2-x-((1/2)*x)-8 = 0
(-1/2)*x-x+13/2-8 = 0
-3/2*x-3/2 = 0 // + 3/2
-3/2*x = 3/2 // : -3/2
x = 3/2/(-3/2)
x = -1
x = -1
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