Chapter 7: Problem 34
Factor completely, if possible. Check your answer. $$10+7 k+k^{2}$$
Short Answer
Expert verified
The short version of the answer is: \( (k+2)(k+5) \)
Step by step solution
01
Factor by Grouping
First, we will rewrite the quadratic expression as a four-term expression by regrouping the two constant terms \(7k\) and \(10\) as \(2k+5k+10\), where the first two terms have the greatest common factor (GCF) of \(k\), and the last two terms, the GCF is 5. So, the expression becomes:
\[k^2 + 2k + 5k + 10\]
02
Factor Each Group Separately
Next, we will factor out the GCF from each group separately:
\[
k(k + 2) + 5(k + 2)
\]
03
Factor the Common Binomial
Now, we have a common binomial \((k + 2)\) in both terms, so we can factor that out:
\[
(k + 2)(k + 5)
\]
So, the factored form of the given expression is \((k+2)(k+5)\).
04
Check Your Answer
Now, we will check our answer by expanding the factored expression to see if it matches the original expression:
\[
(k + 2)(k + 5)= k^2+5k+2k+10 = k^2 + 7k + 10
\]
The factored form \((k+2)(k+5)\) correctly expands back into the original expression \(k^2 + 7k + 10\), so we have successfully factored the expression completely.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Greatest Common Factor (GCF)
Finding the greatest common factor, or GCF, is a key step in factoring expressions. The GCF is the largest factor that can be divided evenly into all terms of a polynomial. When factoring, we first identify the GCF of different parts of the expression.
- In the given expression, the terms were regrouped such that the first two terms were combined and the last two terms were combined.
- For example, in the group \(k^2 + 2k\), the GCF is \(k\).
- In the group \(5k + 10\), the GCF is 5.
Binomial Factorization
Binomial factorization involves looking for binomial expressions that can be factored out of a polynomial. Binomials are polynomial expressions that consist of exactly two terms.
- Once we have identified and factored out the GCF from individual groups, we often search for common binomial factors within the expression.
- In this case, after factoring each group separately, the expression turns into \(k(k + 2) + 5(k + 2)\).
- The common binomial factor here is \((k + 2)\), which appears in both groupings.
Quadratic Expression
A quadratic expression is a polynomial with an exponent of 2 as the highest power of a variable. It typically takes the general form of \(ax^2 + bx + c\).
- In our example exercise, \(k^2 + 7k + 10\) represents a quadratic expression.
- The structure consists of the squared term \(k^2\), a linear term \(7k\), and a constant term, 10.
- Quadratic expressions are often factored to find their roots or to simplify calculations.
Factoring by Grouping
Factoring by grouping is a technique where you group terms in a polynomial to make factoring easier. This method is particularly useful when you have more than three terms or when other methods don't work.
- Our problem begins by regrouping the middle terms \(7k\) into two parts, i.e., \(2k\) and \(5k\), producing \(k^2 + 2k + 5k + 10\).
- Next, we factor each group separately by extracting the GCF, resulting in an expression like \(k(k + 2) + 5(k + 2)\).
- Finally, we notice a common binomial \((k + 2)\) in both groups and factor it out to yield the final, neatly factored form: \((k + 2)(k + 5)\).