If the point (2,1 | 4) is on the image of the function f (x) = 2aX + B, and on the image of its inverse function, find the value of a and B Ax + B means 2

If the point (2,1 | 4) is on the image of the function f (x) = 2aX + B, and on the image of its inverse function, find the value of a and B Ax + B means 2

f(x)=2^(ax+b)
(2,1 / 4) on his inverse function
Then (1 / 4,2) is on f (x)
Two point substitution
1/4=2^(2a+b)
2=2^(a/4+b)
So 2A + B = - 2
a/4+b=1
a=-12/7,b=10/7