Calculate the composite functions f º g and g º f, and determine their domains.
To calculate (f º g)(x) = f(g(x)), substitue into the expression for f(x) and simplify the expression to a single fraction.
(f º g)(x) = f(g(x))
, where a =
Similarly, calculate (g º f)(x) = g(f(x)) by substituting into the expression for g(x) and simplify the expression.
(g º f)(x) = g(f(x))
, where b =
To obtain the domain of either f º g or g º f, we need to find the domain of f(x) and g(x) individually.
Since f(x) and g(x) are both rational functions, the only x-values that need to be excluded are those that make the denominator zero.
For f(x), the denominator is x8 + 1 and is never zero.
Thus the domain of f(x) is
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Since (f º g)(x) = f(g(x)), f(x) takes as inputs the values from g(x) to obtain the domain for
(f º g)(x), we need to intersect the domain of g(x) with the domain of the expression for
(f º g)(x).
Now (f º g)(x) = is a rational function so that the only x-values that need to be excluded are those that make the denominator zero or undefined. The denominator of (f º g)(x) is x-32+1, which is never zero.
Thus the domain of (f º g)(x)= is
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Since (g º f)(x) = g(f(x)), g(x) takes, as inputs, the values from f(x), to find the domain for
(g º f)(x) we need to intersect the domain of f(x) with the domain of the expression for
(g º f)(x).
Now (g º f)(x) = (x8 + 1)4 is a polynomial function, which is defined for all real numbers.
Thus the domain of (g º f)(x) = (x8 + 1)4 is
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