Table of contents
- 0. Review of Algebra4h 16m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 6m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 19m
- 10. Combinatorics & Probability1h 45m
4. Polynomial Functions
Dividing Polynomials
Problem 74
Textbook Question
Find k so that 4x+3 is a factor of 20x^3+23x^2-10x+k.
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Step 1: Since 4x+3 is a factor of the polynomial, we can use the Factor Theorem which states that if a polynomial f(x) has a factor of the form x - a, then f(a) = 0. In this case, our factor is 4x + 3, so we can rewrite it in the form x - a by letting x = -3/4.
Step 2: Substitute x = -3/4 into the polynomial 20x^3+23x^2-10x+k. This will give us the equation 20(-3/4)^3 + 23(-3/4)^2 - 10(-3/4) + k = 0.
Step 3: Simplify the equation to find the value of k. Remember, the equation should equal zero because of the Factor Theorem.
Step 4: After simplifying, you will get an equation in the form k = some number.
Step 5: The number you get is the value of k that makes 4x+3 a factor of the polynomial 20x^3+23x^2-10x+k.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Polynomial Factorization
Polynomial factorization involves expressing a polynomial as a product of its factors. In this context, determining if a polynomial, such as 20x^3 + 23x^2 - 10x + k, can be divided by another polynomial, like 4x + 3, without a remainder is essential. If 4x + 3 is a factor, then the polynomial can be rewritten in a simpler form, which is crucial for solving the problem.
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Remainder Theorem
The Remainder Theorem states that when a polynomial f(x) is divided by a linear divisor of the form (x - c), the remainder of this division is f(c). In this case, to find k such that 4x + 3 is a factor, we can set x = -3/4 (the root of 4x + 3) and ensure that the polynomial evaluates to zero. This theorem provides a straightforward method to check for factors.
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Substitution Method
The substitution method involves replacing a variable in an expression with a specific value to simplify calculations. In this problem, substituting x = -3/4 into the polynomial allows us to create an equation involving k. By solving this equation, we can find the value of k that ensures 4x + 3 is a factor of the given polynomial.
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