4. Adding and Subtracting Rational Expressions
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Recall that we must exclude the values that make the denominator zero.
See solution.
f(x) ± g(x) &= p(x)/q(x) ± r(x)/s(x) [0.1cm] &= p(x)s(x) ± q(x)r(x)/q(x)s(x) Since we got a rational function, we have to exclude the values that make the denominator zero. q(x)s(x) = 0 ⇒ q(x) = 0 s(x) = 0 We see above that the domain of the sum or difference of two rational functions is all the real numbers such that q(x)≠0 and s(x)≠0.
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The domain of the sum or difference of two rational functions is the intersection of the domains of both functions. |