If f of x is equal to x plus 4 and g of x is equal to x squared minus 1 , what is open paren g circ f close paren times x ?

To find (g ∘ f)(x), substitute f(x) = x + 4 into g(x) = x² − 1. This gives g(f(x)) = (x + 4)² − 1 = x² + 8x + 16 − 1 = x² + 8x + 15. Therefore, the correct choice is A, x² + 8x + 15.

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