Chapter 3: Problem 77
Let \(f(x)=-x^{3}+2 x-2\) and \(g(x)=\frac{2-x}{9+x}\) and find each value. $$ f(-1) $$
Short Answer
Expert verified
The value of \( f(-1) \) is \(-3\).
Step by step solution
01
Understand the Function
The function given is \( f(x) = -x^3 + 2x - 2 \). This is a cubic function, and we need to evaluate it at a specific point \( x = -1 \).
02
Substitute the Point into the Function
Substitute \( x = -1 \) into the function \( f(x) \):\[f(-1) = -(-1)^3 + 2(-1) - 2\]
03
Calculate the Cube of Negative One
Calculate \((-1)^3\), which is equal to \(-1\):\[(-1)^3 = -1\]
04
Apply Negation to the Cubic Term
Apply the negation to the cubic term:\[-(-1) = 1\]
05
Calculate the Expression
Substitute the results back into the function evaluation:\[f(-1) = 1 + 2(-1) - 2\]This simplifies to:\[f(-1) = 1 - 2 - 2\]
06
Final Calculation
Combine the constants to find the final result:\[f(-1) = 1 - 2 - 2 = -3\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Evaluation
Evaluating functions means finding the output value of the function for a specific input value. This process is essential in understanding how functions behave at different points. In our exercise, we are tasked with calculating the value of the function \( f(x) = -x^3 + 2x - 2 \) when \( x \) is set to -1.
The process involves several steps:
The process involves several steps:
- First, substitute the given input value into every occurrence of \( x \) in the function expression.
- Perform all arithmetic operations following the order of operations: parentheses, exponents, multiplication/division (from left to right), and addition/subtraction (from left to right).
- The result after all calculations is the output of the function for that specific input value.
Polynomials
Polynomials are mathematical expressions made up of variables, constants, and non-negative integer exponents. These form the backbone of many algebraic operations. In the exercise, the function \( f(x) = -x^3 + 2x - 2 \) is a cubic polynomial because the highest power of \( x \) is 3.
Polynomials have several important characteristics:
Polynomials have several important characteristics:
- Each term in a polynomial is a product of a constant (or coefficient) and a variable raised to an exponent.
- The degree of a polynomial is determined by the highest exponent present.
- Polynomials are smooth, continuous functions, which means they don't have any abrupt changes, holes, or breaks.
- Cubic polynomials like ours have the capacity to change their direction up to two times, forming an 'S' shape or reversed 'S' shape on a graph.
Substitution Method
The substitution method is a fundamental technique often used in algebra to determine the values of a function. It involves replacing a variable with a given value to simplify the equation and solve for another part of it. In this exercise, we used substitution to evaluate the cubic function \( f(x) = -x^3 + 2x - 2 \) by setting \( x = -1 \).
Here's how substitution works in practice:
Here's how substitution works in practice:
- Identify the variable to substitute and replace it in the function with the provided numerical value.
- Adapt the mathematical expression by following the correct order of operations to compute the result.
- If necessary, break down complex calculations into simpler steps to ensure accuracy, especially with negative numbers and powers.