If f(x) = ax+b where a and b are real numbers and if f(f(x)) = 9x + 7 then find a+b .
f (f(x) ) = 9x + 7
This implies that
a ( ax + b) + b = 9x + 7 simplify
(a^2) x +( ab + b) = 9x + 7 equate terms
a^2 = 9
a = 3
And
ab + b = 7
3b + b =7
4b =7
b =7/4
a + b = 3 + 7/4 = 19/4
