apply intermedaite value theorem on x^5-x^3+3x-5
We denote by f(x) the function x5-x3 +3x-5.
f(x) tends to "+\\infty" when x tends to "+\\infty" and tends to "-\\infty" when x tends to "-\\infty"
Applying the intermediate value theorem, we have that this function takes any real values.
f(0)=-5<0 and f(x) tends to "+\\infty" when x tends to "+\\infty".
Applying the intermediate value theorem, we have that there exists a positive root of f(x).
f(1) = -2 < 0 and f(2) = 25 > 0
Applying the intermediate value theorem one time more, we have that one of the roots of f(x) lies in the interval (1,2).
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