The function f is defined by \(f(x) = 2 - \frac{5}{x+2}\) for \(x > -2\).
The function g is defined by \(g(x) = x + 3\) for \(x > 0\).
Obtain an expression for \(fg(x)\) giving your answer in the form \(\frac{ax+b}{cx+d}\), where \(a, b, c\) and \(d\) are integers.
Solution
First, substitute \(g(x) = x + 3\) into \(f(x)\):
\(fg(x) = 2 - \frac{5}{(x+3)+2} = 2 - \frac{5}{x+5}\).
To combine into a single fraction, express \(2\) as \(\frac{2(x+5)}{x+5}\):
\(fg(x) = \frac{2(x+5)}{x+5} - \frac{5}{x+5}\).
Combine the fractions:
\(fg(x) = \frac{2(x+5) - 5}{x+5}\).
Simplify the numerator:
\(2(x+5) - 5 = 2x + 10 - 5 = 2x + 5\).
Thus, \(fg(x) = \frac{2x+5}{x+5}\).
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