Let $f(x) =7x+4$ and g(x) = x-7 how do you find (fog)(x)?

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Answer 1 · 2015-07-19T23:49:46

$(f@g)(x) = f(g(x)) = 7(g(x)) + 4 = 7(x-7) + 4$

$= 7x-49+4 = 7x-45$

It may be less confusing to use different variables in the two function definitions.

For example:

$f(y) = 7y + 4$

$g(x) = x-7$

Then it is clear that we can let $y = g(x)$ to find:

$(f@g)(x) = f(g(x)) = f(y) = 7y+4$

$= 7*g(x)+4 = 7(x-7)+4 = 7x-49+4 = 7x-45$

Let f(x) =7x+4f(x) =7x+4 and g(x) = x-7 how do you find (fog)(x)?