# If f(x)= 2x+1, what is #2f(x+1)?

it will be twice your function evaluated at $x + 1$, i.e.:
$2 \left[2 \left(x + 1\right) + 1\right] = 2 \left[2 x + 2 + 1\right] = 2 \left[2 x + 3\right] = 4 x + 6$