Given f (x) = 4x - 7; g(x) = x +3, what is the value of (g o f) (4)?

1 Answer
Apr 14, 2017

#(g circ f)(4)=color(magenta)(12)#

Explanation:

Within this explanation, I will use the notation #g(f(x))# instead of the given form #(g circ f)#; I find it easier to understand.

If #g(color(blue)x)=color(blue)x+3#
and #color(red)(f(x))=color(red)(4x-7)#
then
#color(white)("XXX")g(color(red)(f(x)))=color(red)(4x-7)+3#

#color(white)("XXXXXXX")=4x-4#

and if #g(f(color(green)x))=4color(green)x-4#
then
#color(white)("XXX")g(f(color(green)4))=4 * color(green)4 -4#

#color(white)("XXXXXXX")=16-4#

#color(white)("XXXXXXX")=12#