# Question #0bd52

Aug 31, 2016

$g \left(a + 3\right) = {a}^{2} + 4 a + 7$

#### Explanation:

When you were younger, the textbook would probably ask you such questions as:

If $f \left(x\right) = 2 x + 1$, evaluate $f \left(3\right)$. You would just substitute $3$ for x:

$f \left(3\right) = 2 \left(3\right) + 1 = 7$

This problem is much the same; you just substitute $a + 3$ for x.

$g \left(a + 3\right) = {\left(a + 3\right)}^{2} - 2 \left(a + 3\right) + 4$

$g \left(a + 3\right) = {a}^{2} + 6 a + 9 - 2 a - 6 + 4$

$g \left(a + 3\right) = {a}^{2} + 4 a + 7$

Hopefully this helps!