# If f(x) = 2x-1 and g(x) = 4x, what is f[g(3)] ?

Feb 5, 2016

$23$

#### Explanation:

By definition of compositions of functions,

$\left(f \circ g\right) \left(x\right) = f \left[g \left(x\right)\right]$

$= f \left(4 x\right)$

$= 8 x - 1$

$\therefore \left(f \circ g\right) \left(3\right) = 8 \left(3\right) - 1$

$= 23$