Question

Let f(x) = x2 and g(x) = x + 5. Write an expression that represents each composition:
a. g(f(4))
b. f(g(4))
c. (f ∘ g)(x)

Answer 1

Answer:

(a) 21

(b) 81

(c) $(fog)x=(x+5)^2=x^2+10x+25$                  

Step-by-step explanation:

We have given the function $f(x)=x^2\ and g(x)=x+5$

(a) We have to write the expression for given composition

$g(f(4))$

Now first we find f(4)

So f(4) = $4^2=16$

So $g(f(4))=g(16)=16+5=21$

(b) $f(g(4))$

Now first we find g(4)

So g(4) = $4+5=9$

So $f(g(4))=f(9)=9^2=81$

$(fog)x=(x+5)^2=x^2+10x+25$