def is_increasing(f, interval=S.Reals, symbol=None):
    """
    Returns if a function is increasing or not, in the given
    ``Interval``.

    Examples
    ========

    >>> from sympy import is_increasing
    >>> from sympy.abc import x, y
    >>> from sympy import S, Interval, oo
    >>> is_increasing(x**3 - 3*x**2 + 4*x, S.Reals)
    True
    >>> is_increasing(-x**2, Interval(-oo, 0))
    True
    >>> is_increasing(-x**2, Interval(0, oo))
    False
    >>> is_increasing(4*x**3 - 6*x**2 - 72*x + 30, Interval(-2, 3))
    False
    >>> is_increasing(x**2 + y, Interval(1, 2), x)
    True

    """
    f = sympify(f)
    free_sym = f.free_symbols

    if symbol is None:
        if len(free_sym) > 1:
            raise NotImplementedError('is_increasing has not yet been implemented '
                                        'for all multivariate expressions')
        if len(free_sym) == 0:
            return True
        symbol = free_sym.pop()

    df = f.diff(symbol)
    df_nonneg_interval = solveset(0 >= df, symbol, domain=S.Reals)
    return interval.is_subset(df_nonneg_interval)
dataset/ETHPy150Open sympy/sympy/sympy/calculus/singularities.py/is_increasing/swapped operands of `>=`