Question

Se considera functia f:R->R f(x) = 2x+m
Aflati m pentru care f(f(1))=5

Answer 1

$\it f(1)=2\cdot1+m=2+m\\ \\ f(f(1))=f(2+m)=2(2+m)+m=4+2m+m=4+3m\ \ \ \ \ (1)\\ \\ f(f(1))=5\ \ \ \ \ (2)\\ \\ \\ 4+3m=5|_{-4} \Rightarrow 3m=1|_{:3} \Rightarrow m=\dfrac{1}{3}$