Question

Найдите f(7), если f(x+5)=2^(4 − x).

Answer 1

$f(x+5)=2^{4-x}; \\vozmem \ x=2,\ togda\ f(7)=2^2=4;$

Answer 2

$f(x+5)=2^{4-x}\\\\f(x)=f(x+5-5)=2^{4-(x-5)}=2^{4-x+5}=2^{9-x}\\\\f(7)=2^{9-7}=2^2=4$