Question

Find a, if f(a) = 5 + 4a and f o f(a) = 57.​

Answer 1

Answer:

$f(f(a)) = 57$

$f(5 + 4a) = 57$

$5 + 4(5 + 4a) = 57$

$5 + 20 + 16a = 57$

$16a = 57 - 25 = 32$

$so \: \: a = \frac{32}{16} = 2$

Ans.