If A times x is equal to 3 x plus 1 and b times x is equal to square root of x minus 4 end root , what is the domain of open paren b circ A close paren times x ?

For the composite function (B ∘ A)(x), the output of A must be allowed as an input to B. Since B(x) = √(x − 4), its input must be at least 4. Substitute A(x) = 3x + 1: 3x + 1 ≥ 4, so x ≥ 1. Therefore, the domain is [1, ∞), choice C.

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