Chapter 2: Problem 6
Given \(g(x)=|2 x|-x^{2}+3,\) find \(g(-x)\).
Short Answer
Expert verified
The function remains the same: \( g(-x) = g(x) = 2|x| - x^{2} + 3 \).
Step by step solution
01
Substitute \( -x \) for \( x \) in the original function
Given the function \( g(x) = |2x| - x^{2} + 3 \), to find \( g(-x) \), we replace \( x \) with \( -x \) in the function. So, \( g(-x) = |2(-x)| - (-x)^{2} + 3 \).
02
Simplify the absolute value term
The absolute value of \( 2(-x) \) simplifies as follows: \( |2(-x)| = |-2x| = 2|x| = 2x \) (since \( |x| \) is always positive). Thus, \( g(-x) = 2|x| - (-x)^{2} + 3 \).
03
Simplify the square term
Next, simplify the square term \( (-x)^{2} \), which is the same as \( x^{2} \). So the function becomes \( g(-x) = 2|x| - x^{2} + 3 \).
04
Combine the results
Putting all simplified terms together, the function remains \( g(-x) = 2|x| - x^{2} + 3 \). Notice this is the same as the original function.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Absolute Value
Understanding absolute value is crucial in college algebra. The absolute value of a number is its distance from zero on the number line, regardless of direction. For any real number, the absolute value of that number is always non-negative.
For example, the absolute value of both -3 and 3 is 3, because both are three units away from zero on the number line.
In equations, when you see something like \(|x|\), it means we're only interested in the magnitude of x, not its sign. This property is used in many algebraic manipulations. In the exercise, we used \(|2(-x)| = 2|x|\), since the absolute value of a negative number doesn't change its absolute value.
For example, the absolute value of both -3 and 3 is 3, because both are three units away from zero on the number line.
In equations, when you see something like \(|x|\), it means we're only interested in the magnitude of x, not its sign. This property is used in many algebraic manipulations. In the exercise, we used \(|2(-x)| = 2|x|\), since the absolute value of a negative number doesn't change its absolute value.
Function Transformation
In algebra, function transformations involve shifting, stretching, compressing, or reflecting the graph of a function. When working with functions, understanding how these transformations work makes it easier to manipulate and solve them.
To find \(g(-x)\) from \(g(x)\), we replaced every instance of x with -x in the function. This resulted in a reflection of the function's graph across the y-axis. However, in our specific example, \(g(x) = |2x| - x^2 + 3\), the function is symmetric, meaning \(g(x) = g(-x)\)
Such transformations are essential for understanding how changes to the input variable (x) affect the output.
To find \(g(-x)\) from \(g(x)\), we replaced every instance of x with -x in the function. This resulted in a reflection of the function's graph across the y-axis. However, in our specific example, \(g(x) = |2x| - x^2 + 3\), the function is symmetric, meaning \(g(x) = g(-x)\)
Such transformations are essential for understanding how changes to the input variable (x) affect the output.
Polynomial Simplification
Simplifying polynomials is a fundamental skill in algebra. It involves combining like terms and performing operations within the polynomial to make it more manageable.
In our exercise, after replacing x with -x in \(g(x) = |2x| - x^2 + 3\), we had to simplify the terms.
In our exercise, after replacing x with -x in \(g(x) = |2x| - x^2 + 3\), we had to simplify the terms.
- The absolute value term \(|2(-x)| = |2x| = 2|x|\).
- The square term \((-x)^2 = x^2\).
Symmetry in Functions
Symmetry in functions helps to understand their behavior and graphing properties. A function is symmetric with respect to the y-axis if \(f(x) = f(-x)\) for all x in the function's domain.
In our example, \(g(x) = 2|x| - x^2 + 3\), after transforming and simplifying \(g(-x)\), we found that it equaled the original function. This indicates that \(g(x)\) is symmetric with respect to the y-axis.
This kind of symmetry simplifies the analysis of functions, as it tells us the graph of \(g(x)\) is a mirror image about the y-axis. Recognizing symmetry can also make it easier to solve equations and understand the nature of the function.
In our example, \(g(x) = 2|x| - x^2 + 3\), after transforming and simplifying \(g(-x)\), we found that it equaled the original function. This indicates that \(g(x)\) is symmetric with respect to the y-axis.
This kind of symmetry simplifies the analysis of functions, as it tells us the graph of \(g(x)\) is a mirror image about the y-axis. Recognizing symmetry can also make it easier to solve equations and understand the nature of the function.