Math Problem Statement

Question content area top Part 1 Find all rational zeros of f. Then​ (if necessary) use the depressed equation to find all roots of the equation ​f(x)equals0. ​f(x)equalsxcubednegative 37xplus 6 Question content area bottom Part 1 Select the correct choice below and fill in the answer box within your choice. A. The set of all zeros of the given function is StartSet nothing EndSet    . ​(Simplify your answer. Type an exact​ answer, using radicals as needed. Use a comma to separate answers as​ needed.) B. There are no real zeros.

Solution

We are given the cubic function f(x)=x337x+6f(x) = x^3 - 37x + 6, and we are tasked with finding all rational zeros, then solving for all roots of the equation f(x)=0f(x) = 0.

Step 1: Rational Root Theorem

The Rational Root Theorem helps to identify possible rational roots of a polynomial. It states that any rational root, written as pq\frac{p}{q}, must satisfy:

  • pp is a factor of the constant term (in this case, 6),
  • qq is a factor of the leading coefficient (in this case, 1).

For f(x)=x337x+6f(x) = x^3 - 37x + 6, the constant term is 6, and the leading coefficient is 1. The possible rational roots are the factors of 6 divided by the factors of 1. Thus, the possible rational roots are: ±1,±2,±3,±6\pm 1, \pm 2, \pm 3, \pm 6

Step 2: Testing Possible Rational Roots

We now test each of the possible rational roots using synthetic division or substitution into f(x)f(x).

Testing x=1x = 1:

f(1)=1337(1)+6=137+6=30(Not a root)f(1) = 1^3 - 37(1) + 6 = 1 - 37 + 6 = -30 \quad (\text{Not a root})

Testing x=1x = -1:

f(1)=(1)337(1)+6=1+37+6=42(Not a root)f(-1) = (-1)^3 - 37(-1) + 6 = -1 + 37 + 6 = 42 \quad (\text{Not a root})

Testing x=2x = 2:

f(2)=2337(2)+6=874+6=60(Not a root)f(2) = 2^3 - 37(2) + 6 = 8 - 74 + 6 = -60 \quad (\text{Not a root})

Testing x=2x = -2:

f(2)=(2)337(2)+6=8+74+6=72(Not a root)f(-2) = (-2)^3 - 37(-2) + 6 = -8 + 74 + 6 = 72 \quad (\text{Not a root})

Testing x=3x = 3:

f(3)=3337(3)+6=27111+6=78(Not a root)f(3) = 3^3 - 37(3) + 6 = 27 - 111 + 6 = -78 \quad (\text{Not a root})

Testing x=3x = -3:

f(3)=(3)337(3)+6=27+111+6=90(Not a root)f(-3) = (-3)^3 - 37(-3) + 6 = -27 + 111 + 6 = 90 \quad (\text{Not a root})

Testing x=6x = 6:

f(6)=6337(6)+6=216222+6=0(Root found!)f(6) = 6^3 - 37(6) + 6 = 216 - 222 + 6 = 0 \quad (\text{Root found!})

So, x=6x = 6 is a root.

Step 3: Depressed Equation

Now that we know x=6x = 6 is a root, we can factor (x6)(x - 6) from the polynomial. To do this, we perform synthetic division on f(x)=x337x+6f(x) = x^3 - 37x + 6 by (x6)(x - 6).

Performing synthetic division:

6 & 1 & 0 & -37 & 6 \\ & & 6 & 36 & -6 \\ \hline & 1 & 6 & -1 & 0 \\ \end{array}$$ The quotient is $$x^2 + 6x - 1$$. So, we can write: $$f(x) = (x - 6)(x^2 + 6x - 1)$$ ### Step 4: Solving the Quadratic Equation Next, solve $$x^2 + 6x - 1 = 0$$ using the quadratic formula: $$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$ For $$x^2 + 6x - 1 = 0$$, we have $$a = 1$$, $$b = 6$$, and $$c = -1$$. Substituting into the quadratic formula: $$x = \frac{-6 \pm \sqrt{6^2 - 4(1)(-1)}}{2(1)} = \frac{-6 \pm \sqrt{36 + 4}}{2} = \frac{-6 \pm \sqrt{40}}{2} = \frac{-6 \pm 2\sqrt{10}}{2}$$ $$x = -3 \pm \sqrt{10}$$ ### Step 5: Final Answer Thus, the three roots of the equation are: $$x = 6, \quad x = -3 + \sqrt{10}, \quad x = -3 - \sqrt{10}$$ ### Final Answer: The set of all zeros is: $$\{6, -3 + \sqrt{10}, -3 - \sqrt{10}\}$$ Would you like further details or explanations? --- Here are some related questions to deepen understanding: 1. What are the conditions for using the Rational Root Theorem? 2. How does synthetic division help in factoring polynomials? 3. What is the significance of a "depressed equation" in solving polynomials? 4. How can you verify that the solutions to the quadratic are correct? 5. What are the differences between rational and irrational roots? **Tip:** Always verify potential roots by substituting them back into the original equation to avoid calculation errors.

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Math Problem Analysis

Mathematical Concepts

Algebra
Cubic Polynomials
Synthetic Division
Quadratic Equations

Formulas

Rational Root Theorem
Quadratic Formula: x = (-b ± √(b^2 - 4ac)) / 2a

Theorems

Rational Root Theorem

Suitable Grade Level

Grades 10-12