Chapter 8: Problem 7
Factor each of the following expressions as completely as possible. If an expression is not factorable, say so. $$x^{2}+3 x-2$$
Short Answer
Expert verified
\[(x - 1)(x + 4)\]
Step by step solution
01
Identify coefficients
Identify the coefficients of the quadratic expression in the standard form quadratic expression: \[x^{2} + 3x - 2\] This expression is in the form \[ax^{2} + bx + c\]. Here, \[a = 1,\] \[b = 3,\] \[c = -2\].
02
Find the product of ac
Multiply the coefficient of \(x^2\) (which is a) and the constant term (which is c): \[a \times c = 1 \times -2 = -2\].
03
Find factors of ac that sum to b
Look for two numbers that multiply to \[-2\] and add up to \[b = 3\]. The numbers are \[4\] and \[-1\] because \[4 \times -1 = -2\] and \[4 + (-1) = 3\].
04
Rewrite the middle term
Split the middle term \(3x\) into \[4x - x\] using the factors found: \[x^2 + 4x - x - 2.\]
05
Factor by grouping
Group terms to factor each part separately: \[(x^2 + 4x) - (x + 2).\]Factor out the greatest common factor from each group: \[x(x + 4) - 1(x + 4).\]
06
Factor out the common binomial factor
Factor out \(x + 4\): \[(x - 1)(x + 4)\]
07
Final Factored Form
The final factored form of the expression \[x^2 + 3x - 2\] is: \[(x - 1)(x + 4).\]
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
quadratic expression
A quadratic expression is a polynomial of degree 2.
This means the highest power of the variable (usually x) is 2.
Quadratic expressions have the form: \[ax^2 + bx + c\].
Here, a, b, and c are constants, and a is not zero.
In the example, \[x^2 + 3x - 2\], we identify:
This means the highest power of the variable (usually x) is 2.
Quadratic expressions have the form: \[ax^2 + bx + c\].
Here, a, b, and c are constants, and a is not zero.
In the example, \[x^2 + 3x - 2\], we identify:
- a = 1
- b = 3
- c = -2
factoring by grouping
Factoring by grouping is a method used to factor some polynomials.
It involves rearranging terms into groups that can each be factored separately.
Here's how it works step by step for \[x^2 + 3x - 2\]:
It involves rearranging terms into groups that can each be factored separately.
Here's how it works step by step for \[x^2 + 3x - 2\]:
- Split the middle term using two numbers that multiply to a * c (-2) and add up to b (3).
In our case, 4 and -1 work.
So, rewrite the expression as\[x^2 + 4x - x - 2\]. - Group the terms:\[(x^2 + 4x) + (-x - 2)\].
- Factor each group:
\[x(x + 4) - 1(x + 4)\]. - Factor out the common binomial factor:
\[x + 4\]. - Combine to get: \[(x - 1)(x + 4)\].
standard form of quadratic
The standard form of a quadratic equation is \[ax^2 + bx + c = 0\].
It's helpful because it sets a framework for solving quadratics using various methods like factoring, completing the square, or using the quadratic formula.
When we have a quadratic expression like \[x^2 + 3x - 2\]:
It's helpful because it sets a framework for solving quadratics using various methods like factoring, completing the square, or using the quadratic formula.
When we have a quadratic expression like \[x^2 + 3x - 2\]:
- It's already in standard form \[ax^2 + bx + c\].
- We identified the coefficients as:
\[a = 1,\ b = 3,\ c = -2\].