Problem 21 - Algebra 1

Question

Divide. Divide \(9 a^{2}-54 a-36\) by \(3 a\).

Step-by-Step Solution

Answer

The result of dividing \(9 a^{2}-54 a-36\) by \(3 a\) is \(3a -18 - \frac{12}{a}\).

Step 1: Identify the Terms in the Polynomial

There are three terms in the polynomial in the numerator, which are \(9 a^{2}\), \(-54 a\), and \(-36\). We will divide each term separately by \(3 a\).

Step 2: Divide Each Term by the Monomial

Divide \(9 a^{2}\) by \(3 a\), divide \(-54 a\) by \(3 a\), and then divide \(-36\) by \(3 a\). That gives us \(3a\), \(-18\), \(-12/a\) respectively.

Step 3: Write the Final Answer

The final answer is obtained by writing down these solved terms together separated by a minus sign, which gives us \(3a -18 - \frac{12}{a}\)

Key Concepts

Understanding Monomials

In mathematics, a monomial is an algebraic expression that consists of a single term. It can be made up of numbers, variables, or the product of numbers and variables. A monomial is very straightforward, like having one word out of a sentence. An example would be something like \(3x\) or \(-7\).

When discussing or dealing with polynomials, it is important to recognize what a monomial is. This is because when dividing polynomials, as in our example, each term in the polynomial needs to be matched against the divider, which is often a monomial.

• Example 1: \(4x^2\) is a monomial, where "4" is the coefficient, and \(x^2\) is the variable part.
• Example 2: \(-5\) is also a monomial as it is a single numerical term.

In our original problem, the divisor \(3a\) is a monomial, and it plays a crucial role in splitting the given polynomial into simpler parts.

Identifying Terms in Polynomials

A polynomial is made up of one or more terms. Unlike monomials, polynomials can combine several terms through addition or subtraction. Each term within a polynomial can have its own unique power and coefficient. Identifying these parts is the first step when performing operations like division.

• Each term in a polynomial can have a coefficient (a number) and variables raised to a power.
• Examples of terms are \(9a^2\), \(-54a\), and \(-36\). In these examples, \(9a^2\) is a term with a coefficient of 9 and a variable \(a\) raised to the power of 2.

In the context of polynomial division, recognizing these terms allows us to systematically divide each term separately by the monomial divisor. This breakdown simplifies complex expressions and helps to reorganize them into a more digestible form.

Exploring Rational Expressions

Rational expressions are a type of algebraic expression that can be seen as a fraction where both the numerator and the denominator are polynomials. They are an essential concept when dealing with dividing polynomial terms because the result often takes the form of a rational expression.

• A rational expression can look like \(\frac{2x+3}{x-1}\).
• They can be simplified by factorizing both the numerator and the denominator, then reducing common factors.

In our solved exercise, when we divided \(9a^2-54a-36\) by \(3a\), the terms \(\frac{9a^2}{3a}\), \(\frac{-54a}{3a}\), and \(\frac{-36}{3a}\) each form a rational expression initially. Upon simplification, these expressions yield the final outcome of \(3a -18 - \frac{12}{a}\), showcasing how polynomial division can sometimes lead to simplified rational expressions.