Chapter 6: Problem 85
Explain how to factor \(x^{2}+8 x+15\)
Short Answer
Expert verified
The factored form of the trinomial \(x^{2}+8 x+15\) is \((x+3)(x+5)\)
Step by step solution
01
Identify Coefficients
In the given expression \(x^{2}+8 x+15\), the coefficients are 1 (in front of \(x^2\)), 8 (in front of x) and 15 (the constant term).
02
Find Two Numbers
Look for two numbers that multiply to 15 (the third coefficient/the constant) and sum to 8 (the second coefficient). The numbers that fit this criteria are 3 and 5. Because 3*5=15 and 3+5=8.
03
Factor the Trinomial
The trinomial is factored as \((x+3)(x+5)\), because both when multiplied together give the original trinomial \(x^{2}+8 x+15\), and when added together yield 8x.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Trinomial
A trinomial is a specific type of polynomial that consists of three distinct terms. In mathematical expressions, each term may include variables and coefficients. The standard format for a trinomial generally is expressed as:
- A variable squared term, such as \(x^2\)
- A linear variable term, such as \(8x\)
- A constant, such as 15
Coefficients
In the expression \(x^2 + 8x + 15\), coefficients are the numerical factors that multiply the variables in each term. They provide important information about the term's overall value:
- The coefficient of the squared term \(x^2\) is 1. Often implicit, but equally essential.
- The linear term \(8x\) has a coefficient of 8.
- The constant term \(15\) serves as both the third term and a coefficient, though it lacks variables.
Factoring Process
The goal of factoring a trinomial expression like \(x^2 + 8x + 15\) is to rewrite it as a product of two binomials. This process breaks down into manageable steps to identify key values:
- First, analyze the constant term, 15, looking for two numbers that multiply to it. Think of 3 and 5 since \(3 \times 5 = 15\).
- The next step is to verify that these numbers add up to the middle coefficient, 8. Verify by calculating \(3 + 5 = 8\).
- Once identified, the expression can be rewritten as \((x + 3)(x + 5)\), because these numbers satisfy the conditions.
Quadratic Expressions
Quadratic expressions form the backbone of many algebraic concepts and are characterized by the highest variable being squared, such as in \(x^2 + 8x + 15\). They usually come in the form of \(ax^2 + bx + c\):
- "\(a\)" represents the coefficient of the squared term \(x^2\).
- "\(b\)" is the coefficient of the linear term \(x\).
- "\(c\)" is the constant or the coefficient without variables.