Chapter 3: Problem 16
Use the factor theorem to show that \(x-c\) is a factor of \(f(x)\). $$f(x)=x^{4}-3 x^{3}-2 x^{2}+5 x+6 ; \quad c=2$$
Short Answer
Expert verified
Yes, \(x-2\) is a factor of \(f(x)\) because \(f(2) = 0\).
Step by step solution
01
State the Factor Theorem
The Factor Theorem states that \(x-c\) is a factor of a polynomial \(f(x)\) if and only if \(f(c) = 0\). In this exercise, we need to find whether \(x-2\) is a factor of the given polynomial \(f(x)\) by evaluating \(f(2)\).
02
Substitute and Evaluate f(c)
Substitute \(c = 2\) into the polynomial \(f(x) = x^4 - 3x^3 - 2x^2 + 5x + 6\). Calculate \(f(2)\):\[f(2) = (2)^4 - 3(2)^3 - 2(2)^2 + 5(2) + 6\]
03
Calculate Each Term
Break down and calculate each term separately:- \((2)^4 = 16\)- \(-3(2)^3 = -24\)- \(-2(2)^2 = -8\)- \(5(2) = 10\)- \(+6 = 6\)
04
Sum the Results
Add all the calculated terms together to find \(f(2)\):\[f(2) = 16 - 24 - 8 + 10 + 6\]
05
Simplify the Expression
Simplify the expression by performing the arithmetic:\[f(2) = (16 - 24) + (10 - 8) + 6 = -8 + 2 + 6 = 0\]
06
Conclusion
Since \(f(2) = 0\), according to the Factor Theorem, \(x-2\) is a factor of \(f(x)\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polynomial
A polynomial is an algebraic expression made up of variables and coefficients, combined using addition, subtraction, multiplication, and non-negative integer exponents. They serve as fundamental building blocks in mathematics, representing a vast range of problems and scenarios.
Examples of polynomials include:
Examples of polynomials include:
- Quadratic polynomials like \(ax^2 + bx + c\)
- Cubic polynomials such as \(ax^3 + bx^2 + cx + d\)
- Higher-degree polynomials like \(a_nx^n + a_{n-1}x^{n-1} + \ldots + a_1x + a_0\)
Polynomial Roots
The roots of a polynomial are the values of \(x\) which make the polynomial equal to zero. These are also known as "zeros" or "solutions." Finding the roots of a polynomial is essentially solving the equation \(f(x) = 0\).
Identifying the roots of a polynomial is important because:
Identifying the roots of a polynomial is important because:
- They indicate where the graph of the polynomial crosses the x-axis.
- Roots are essential in understanding the behavior of the polynomial function.
- They are critical in engineering and physics for solving real-world problems.
Synthetic Division
Synthetic division is a simplified method of dividing a polynomial by a linear divisor of the form \(x-c\). It is faster and more efficient than traditional long division when working with polynomials and is often used when applying the Factor Theorem.
The process of synthetic division involves:
The process of synthetic division involves:
- Writing down the coefficients of the polynomial.
- Using the root \(c\) as a divisor.
- Performing a sequence of multiplications and additions to find the quotient and remainder.