Question
upstudy study bank question image url

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.)

Ask by Haynes Reyes. in the United States
Dec 08,2024

Upstudy AI Solution

Tutor-Verified Answer

Answer

(a) The possible rational roots are D. \( \pm 1, \pm 2, \pm 4 \). (b) One rational root of the equation is -4.

Solution

To solve the equation \( x^{3}-17 x-4=0 \) using the Rational Root Theorem, we first identify the possible rational roots. ### (a) List all rational roots that are possible according to the Rational Zero Theorem. The Rational Root Theorem states that any rational solution, in the form of \( \frac{p}{q} \), must have \( p \) as a factor of the constant term (which is -4) and \( q \) as a factor of the leading coefficient (which is 1). The factors of -4 (the constant term) are: - \( \pm 1 \) - \( \pm 2 \) - \( \pm 4 \) The factors of 1 (the leading coefficient) are: - \( \pm 1 \) Thus, the possible rational roots are: \[ \pm 1, \pm 2, \pm 4 \] So the correct answer is: **D. \( \pm 1, \pm 2, \pm 4 \)** ### (b) Use synthetic division to test several possible rational roots in order to identify one actual root. Let's test the possible rational roots using synthetic division. We will start with \( x = 1 \): **Testing \( x = 1 \):** \[ \begin{array}{r|rrrr} 1 & 1 & 0 & -17 & -4 \\ & & 1 & 1 & -16 \\ \hline & 1 & 1 & -16 & -20 \\ \end{array} \] The remainder is -20, so \( x = 1 \) is not a root. **Testing \( x = -1 \):** \[ \begin{array}{r|rrrr} -1 & 1 & 0 & -17 & -4 \\ & & -1 & 1 & 16 \\ \hline & 1 & -1 & -16 & 12 \\ \end{array} \] The remainder is 12, so \( x = -1 \) is not a root. **Testing \( x = 2 \):** \[ \begin{array}{r|rrrr} 2 & 1 & 0 & -17 & -4 \\ & & 2 & 4 & -26 \\ \hline & 1 & 2 & -13 & -30 \\ \end{array} \] The remainder is -30, so \( x = 2 \) is not a root. **Testing \( x = -2 \):** \[ \begin{array}{r|rrrr} -2 & 1 & 0 & -17 & -4 \\ & & -2 & 4 & 26 \\ \hline & 1 & -2 & -13 & 22 \\ \end{array} \] The remainder is 22, so \( x = -2 \) is not a root. **Testing \( x = 4 \):** \[ \begin{array}{r|rrrr} 4 & 1 & 0 & -17 & -4 \\ & & 4 & 16 & -4 \\ \hline & 1 & 4 & -1 & -8 \\ \end{array} \] The remainder is -8, so \( x = 4 \) is not a root. **Testing \( x = -4 \):** \[ \begin{array}{r|rrrr} -4 & 1 & 0 & -17 & -4 \\ & & -4 & 16 & 4 \\ \hline & 1 & -4 & -1 & 0 \\ \end{array} \] The remainder is 0, so \( x = -4 \) is a root. Thus, one rational root of the given equation is: \[ \boxed{-4} \]

Answered by UpStudy AI and reviewed by a Professional Tutor

error msg
Explain
Simplify this solution

Extra Insights

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 \( x = -4 \).

Try Premium now!
Try Premium and ask Thoth AI unlimited math questions now!
Maybe later Go Premium
Study can be a real struggle
Why not UpStudy it?
Select your plan below
Premium

You can enjoy

Start now
  • Step-by-step explanations
  • 24/7 expert live tutors
  • Unlimited number of questions
  • No interruptions
  • Full access to Answer and Solution
  • Full Access to PDF Chat, UpStudy Chat, Browsing Chat
Basic

Totally free but limited

  • Limited Solution
Welcome to UpStudy!
Please sign in to continue the Thoth AI Chat journey
Continue with Email
Or continue with
By clicking “Sign in”, you agree to our Terms of Use & Privacy Policy