Answer the following questions about the equation below. \( x^{3}-17 x-4=0 \) (a) List all rational roots that are possible according to the Rational Zero Theorem. Choose the correct answer below. A. \( \pm 1 \) B. \( \pm 4 \) C. \( -1,-2,-4 \) D. \( \pm 1, \pm 2, \pm 4 \) (b) Use synthetic division to test several possible rational roots in order to identify one actual root. One rational root of the given equation is (Simplify your answer.)
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To find all possible rational roots using the Rational Root Theorem, we look at the factors of the constant term (-4) and the leading coefficient (1). The factors of -4 are: \( \pm 1, \pm 2, \pm 4 \). So, the correct answer is D. \( \pm 1, \pm 2, \pm 4 \). Now, let’s apply synthetic division to test some of these possible roots. Testing \( x = 2 \): \[ \begin{array}{r|rrr} 2 & 1 & 0 & -17 & -4 \\ & & 2 & 4 & -26 \\ \hline & 1 & 2 & -13 & -30 \\ \end{array} \] Since the remainder is not zero, 2 is not a root. Testing \( x = 1 \): \[ \begin{array}{r|rrr} 1 & 1 & 0 & -17 & -4 \\ & & 1 & 1 & -16 \\ \hline & 1 & 1 & -16 & -20 \\ \end{array} \] Again, the remainder is not zero. Testing \( x = -1 \): \[ \begin{array}{r|rrr} -1 & 1 & 0 & -17 & -4 \\ & & -1 & 1 & 16 \\ \hline & 1 & -1 & -16 & 12 \\ \end{array} \] Still not a root. Now testing \( x = -4 \): \[ \begin{array}{r|rrr} -4 & 1 & 0 & -17 & -4 \\ & & -4 & 16 & 4 \\ \hline & 1 & -4 & -1 & 0 \\ \end{array} \] The remainder is zero, thus one rational root of the equation is \( x = -4 \).