What is the solution of the fraction with numerator x squared minus 1 and denominator x squared plus 5 x plus 4 is less than or equal to 0 ?

Factor the numerator and denominator: (x² − 1)/(x² + 5x + 4) = (x − 1)(x + 1)/[(x + 1)(x + 4)]. The expression is undefined at x = −1 and x = −4, so both values must be excluded. After canceling the common factor, (x − 1)/(x + 4) is less than or equal to zero on −4 < x ≤ 1; excluding −1 gives the interval in choice B.

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