A question relating to function

Question

Let f(x)=√x and g(x)= 3x+b. What is the value of b if we know that the graph f(g(x)) passes through the point (4,8)

Answer 1

f(g(4)) = 8  is given.

 

g(4) = 3(4) + b = 12 + b

 

f(g(4)) = sqrt( 12 + b) = 8

 

        12 + b = 64

 

     b = 52