Question

f(x)=x+5 and g(x)=x^2. Find (g . f)(4)

Answer 1

\(f\circ g\) or \(f\times g\) ?

Answer 2

the first one

Answer 3

@satellite73

Answer 4

start by getting rid of the circle notation and write
\[f\circ g(x)=f(g(x))\] you should always start that way

Answer 5

then replace the general \(g\) by the specific one you have, in this case it is
\[g(x)=x^2\] so you get \(f(x^2)\)

Answer 6

since \(f(x)=x+5\) you get \(f(x^2)=x^2+5\)

Answer 7

but i just looked above and in your problem you only need \(f\circ g(4)\) so first find \(g(4)=4^2=16\)

Answer 8

then take \(f(16)=16+5=21\)

Answer 9

notice that you will get the same answer if you replace \(x\) by \(4\) in the function \(x^2+5\)
either way

Answer 10

yeah