Question

Learn with an example

Find (fog)(x).
f(x) = 5x
g(x) = 4x
Write your answer as a polynomial in simplest form.
(fºg)(x) = 1
Submit
Not feeling ready yet? These can help:
Composition of linear and quadratic functions: find an equation

Answer 1

`\large{\textbf{f(g(x)) = 20}\\}`

Explanation:

`\large{\textup{Given}:\\$f(x) = 5x $ \hspace{5mm} \& \hspace{5mm} $g(x) = 4x $\\$$ f \circ g(x) = f(g(x))  $$\\$ \implies f(g(x)) = f(5x) $\\\textup{i.e., To substitute $5x$ instead of $x$ in $f(x)$}\\$\implies f(5(x)) = 4(5(x)) = 20x \\ $\textup{Now,}$f(g(1)) = 20(1) =20$}`