a(x) = 3x + 1
b(x) = [tex]\sqrt{x- 4}[/tex]
(b . a)(x) = [tex](3x + 1).\sqrt{x - 4}[/tex]
(b . a)(x) = [tex]3x\sqrt{x-4} + \sqrt{x - 4}[/tex]
We know some things:
There's no square root of a negative number, so,
x - 4 ≥ 0
x ≥ 4
This way, we can say that the domain of (b . a)(x) is:
Dom (b . a)(x) = R ≥ 4
All real numbers higher or equal to 4.
