Answer :

Answer:

f(3)=21

Step-by-step explanation:

f(1)=3

f(n)=2f(n-1)+3

n=2

f(2)=2f(2-1)+3

f(2)=2f(1)+3

f(2)=2*3+3

f(2)=6+3

f(2)=9

n=3

f(3)=2f(3-1)+3

f(3)=2f(2)+3

f(3)=2*9+3

f(3)=18+3

f(3)=21