Chapter 6: Problem 44
$$\text { In Exercises } 43-66, \text { factor completely.}$$ $$3 x^{2}+21 x+36$$
Short Answer
Expert verified
The completely factored form of the expression \(3x^{2} + 21x + 36\) is \(3(x+4)(x+3)\).
Step by step solution
01
Identify common factors
In the quadratic expression \(3x^{2} + 21x + 36\), 3 is a common factor to all terms. So, divide the entire term by 3 to remove the common factor.
02
Rewrite the expression
The expression can be written as \(3(x^{2} + 7x + 12)\).
03
Factor the bracketed polynomial
The polynomial inside the brackets, \(x^{2} + 7x + 12\), is a simple trinomial which can be factored as \((x+4)(x+3)\).
04
Write down the final factored form
So, the completely factored form of the expression is \(3(x+4)(x+3)\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Common Factors
When dealing with polynomials or quadratics, looking for a common factor is often the first and crucial step. A common factor is a term that divides each term of the polynomial without leaving a remainder. In our example, the quadratic expression given was \(3x^{2} + 21x + 36\). You can easily see that each of these terms - 3, 21, and 36 - can be divided by the number 3.Recognizing common factors can simplify your expression, making the factoring process more manageable. Once you identify a common factor, factor it out, which means you divide every term in the polynomial by this number and rewrite the expression:
- The term \(3x^{2}\) becomes \(x^{2}\) when divided by 3.
- The term \(21x\) becomes \(7x\) when divided by 3.
- And the term \(36\) becomes \(12\).
Trinomial Factoring
Trinomial factoring involves breaking down a trinomial into a product of simpler binomials. The trinomial in our example is \(x^{2} + 7x + 12\). The goal is to find two binomials \((x + a)(x + b)\) such that when multiplied out, they yield the original trinomial.There are two important guidelines in trinomial factoring:
- The sum of \(a\) and \(b\) should be equal to the coefficient of the middle term (in this case, 7).
- The product of \(a\) and \(b\) should be equal to the constant term (in this case, 12).
Polynomial Expressions
A polynomial expression is a mathematical expression involving a sum of powers in one or more variables multiplied by coefficients. In our exercise, we worked with a quadratic polynomial, which is a polynomial of degree 2, meaning the highest power of the variable \(x\) is 2.Understanding polynomial expressions is crucial because:
- They are foundational to algebra and appear in many areas of mathematics.
- They can be used to model real-world situations and solve problems involving curves and shapes.