Given f(x) = 7x^2 - 5x, g(x) = 17x - 4 how do you find (fog)(6)?

1 Answer
Alan P.
May 16, 2018

(fcircg)(6)=66,738

Explanation:

(fcircg)(x) can be written as f(color(blue)(g(color(red)x)))

If color(blue)(g(color(red)x))=17color(red)x-4
then color(blue)(g(color(red)6))=17 * color(red)6 -4 = color(blue)(98)

and if (fog)(color(blue)x)=f(color(blue)x)=7color(blue)x^2-5color(blue)x
then (fog)(color(blue)x)=f(color(blue)(g(color(red)x)))=7color(blue)(g(color(red)x))^2-5color(blue)(g(color(red)x))
and
color(white)("then ")(fcircg)(color(blue)x)=f(color(blue)(g(color(red)6)))=7 * color(blue)(98)^2 - 5 * color(blue)(98)=66738
(I used a calculator for the last evaluation)

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