Problem 29 - Algebra 2

Question

Simplify. $$ \frac{4 x^{3}+5 x^{2}-3 x+1}{4 x+1} $$

Step-by-Step Solution

Answer

\( x^2 + x - 1 + \frac{2}{4x + 1} \)

Step 1: Set up the division

To simplify the expression \( \frac{4x^3 + 5x^2 - 3x + 1}{4x + 1} \), we use polynomial long division. Write \( 4x^3 + 5x^2 - 3x + 1 \) as the dividend and \( 4x + 1 \) as the divisor.

Step 2: Divide the leading terms

Divide the leading term of the dividend, \( 4x^3 \), by the leading term of the divisor, \( 4x \). This gives: \( x^2 \).

Step 3: Multiply and subtract

Multiply \( x^2 \) by the entire divisor \( 4x + 1 \), which results in \( 4x^3 + x^2 \). Subtract this from the original dividend: \( 4x^3 + 5x^2 - 3x + 1 - (4x^3 + x^2) = 4x^2 - 3x + 1 \).

Step 4: Repeat the division

Take the new leading term \( 4x^2 \) and divide by \( 4x \) which gives \( x \). Multiply \( x \) with \( 4x + 1 \) to get \( 4x^2 + x \). Subtract this from the current dividend to get \( 4x^2 - 3x + 1 - (4x^2 + x) = -4x + 1 \).

Step 5: Final division

Divide \( -4x \) by \( 4x \), resulting in \( -1 \). Multiply \( -1 \) by \( 4x + 1 \) to get \( -4x - 1 \). Subtract this from the current remainder: \( -4x + 1 - (-4x - 1) = 2 \).

Step 6: State the quotient and remainder

The quotient from the division process is \( x^2 + x - 1 \) and the remainder is \( 2 \). Thus, the simplified expression is \( x^2 + x - 1 + \frac{2}{4x + 1} \).

Key Concepts

Polynomial Division

Polynomial Division is a method used to divide one polynomial by another, similar to the way we divide numbers. In this context, a polynomial is an algebraic expression featuring variables and constants, constructed using operations of addition, subtraction, and multiplication. The key goal of Polynomial Division is to find a quotient and a remainder, much like in traditional arithmetic division.

The process follows a sequence of steps:

• Set up the Division: Position the dividend (the polynomial to be divided) and the divisor (the polynomial by which you divide).
• Divide the Leading Terms: Take the leading term of the dividend and divide it by the leading term of the divisor. This yields the first term of the quotient.
• Multiply and Subtract: Multiply the entire divisor by the first term derived, subtract the result from the dividend, and bring down the next term for the following division.
• Repeat: Continue the process with the new dividend formed from subtraction until there are no terms left to bring down.

The result is a quotient and possibly a remainder, noted in the form \( \text{Quotient} + \frac{\text{Remainder}}{\text{Divisor}} \). This approach ensures a systematic method for simplifying complex polynomial expressions.

Remainder Theorem

The Remainder Theorem provides a quick way to evaluate the remainder of a polynomial division without going through the entire division process. It states that when a polynomial \( f(x) \) is divided by a linear divisor \( (x - c) \), the remainder of this division is simply \( f(c) \).

This theorem has practical applications:

• Evaluating Polynomials: Quickly determine the remainder by substituting \( c \) into the polynomial.
• Verifying Factors: If the remainder is zero when \( f(c) \) is calculated, \( (x - c) \) is a factor of the polynomial.

This principle helps verify division results quickly and confirms the division was performed correctly. In polynomial simplification tasks, even if the divisor is not linear, like in our example, understanding this theorem clarifies the division outcome where the quotient and remainder make up the entire polynomial expression.

Algebraic Expressions

Algebraic Expressions are combinations of numbers, variables, and arithmetic operations. They form the foundational elements of algebra, representing real-world situations and abstract mathematical concepts. An algebraic expression can be as simple as a single number or variable, or more complex, like the polynomial \( 4x^3 + 5x^2 - 3x + 1 \) in our example.

Key components include:

• Constants: Fixed values such as 1 or 4.
• Variables: Symbols like \( x \) that represent unknown numbers.
• Coefficients: Numbers that multiply the variables, like 4 in \( 4x^3 \).
• Terms: Parts of the expression separated by "+" or "-", e.g., \( 4x^3 \) and \( 5x^2 \).

Understanding algebraic expressions is vital for simplifying, evaluating, and solving equations. They are the language through which many mathematical concepts are communicated. Mastery of these forms allows mathematicians and students alike to model and tackle a variety of mathematical problems efficiently.