Help with function question

Question

For all values of x, f(x) = 3x+k, where k is a constant.

Given that ff(3) = 7, find the value of k.

Cheers for any help :)

Answer 1

f(x) = 3x+k

 

Plug in the given point, (3, f(3)) = (3,7):

 

f(x) = 3x+k

7 = 3 + k

 

Solve for k.