(fcircg)(x)(f∘g)(x) can be written as f(color(blue)(g(color(red)x)))f(g(x))
If color(blue)(g(color(red)x))=17color(red)x-4g(x)=17x−4
then color(blue)(g(color(red)6))=17 * color(red)6 -4 = color(blue)(98)g(6)=17⋅6−4=98
and if (fog)(color(blue)x)=f(color(blue)x)=7color(blue)x^2-5color(blue)x(fog)(x)=f(x)=7x2−5x
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))(fog)(x)=f(g(x))=7g(x)2−5g(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)=66738then (f∘g)(x)=f(g(6))=7⋅982−5⋅98=66738
(I used a calculator for the last evaluation)