# Let f(x) = 3x + 8 and g(x) = x^2 + 5, find (f g)(x) ?

May 15, 2018

$f \left(g \left(x\right)\right) = 3 {x}^{2} + 20$

#### Explanation:

Given that, $f \left(x\right) = 3 x + 8 \mathmr{and} g \left(x\right) = {x}^{2} + 5$.

Now, $f \left(g \left(x\right)\right)$

$= 3 \cdot g \left(x\right) + 8$

$= 3 \cdot \left({x}^{2} + 5\right) + 5$

$= 3 {x}^{2} + 15 + 5$

$= 3 {x}^{2} + 20$