Chapter 1: Problem 22
Use the given function \(f\) to find and simplify the following: \- \(f(2)\) \- \(2 f(a)\) \- \(f\left(\frac{2}{a}\right)\) \- \(f(-2)\) \- \(f(a+2)\) -\(\frac{f(a)}{2}\) \- \(f(2 a)\) \- \(f(a)+f(2)\) \- \(f(a+h)\) $$f(x)=3 x^{2}+3 x-2$$
Short Answer
Expert verified
\(f(2)=16\), \(2f(a)=6a^2+6a-4\), \(f\left(\frac{2}{a}\right)=\frac{12}{a^2}+\frac{6}{a}-2\), \(f(-2)=4\), \(f(a+2)=3a^2+15a+16\), \(\frac{f(a)}{2}=\frac{3a^2}{2}+\frac{3a}{2}-1\), \(f(2a)=12a^2+6a-2\), \(f(a)+f(2)=3a^2+3a+14\), \(f(a+h)=3a^2+6ah+3h^2+3a+3h-2\).
Step by step solution
01
Evaluate \(f(2)\)
To find \(f(2)\), substitute \(x = 2\) into the function: \(f(x) = 3x^2 + 3x - 2\). Thus, \(f(2) = 3(2)^2 + 3(2) - 2 = 3 \times 4 + 6 - 2 = 12 + 6 - 2 = 16\).
02
Compute \(2f(a)\)
Substitute \(x = a\) into the function to find \(f(a)\), then multiply the result by 2. \(f(a) = 3a^2 + 3a - 2\). So, \(2f(a) = 2(3a^2 + 3a - 2) = 6a^2 + 6a - 4\).
03
Evaluate \(f\left(\frac{2}{a}\right)\)
Substitute \(x = \frac{2}{a}\) into the function. \(f\left(\frac{2}{a}\right) = 3\left(\frac{2}{a}\right)^2 + 3\left(\frac{2}{a}\right) - 2 = 3\left(\frac{4}{a^2}\right) + \frac{6}{a} - 2 = \frac{12}{a^2} + \frac{6}{a} - 2\).
04
Evaluate \(f(-2)\)
Substitute \(x = -2\) into the function: \(f(x) = 3x^2 + 3x - 2\). Therefore, \(f(-2) = 3(-2)^2 + 3(-2) - 2 = 3 \times 4 - 6 - 2 = 12 - 6 - 2 = 4\).
05
Evaluate \(f(a+2)\)
Substitute \(x = a+2\) into the function. \(f(a+2) = 3(a+2)^2 + 3(a+2) - 2\). First, expand \((a+2)^2 = a^2 + 4a + 4\). Then, \(3(a^2 + 4a + 4) + 3(a+2) - 2 = 3a^2 + 12a + 12 + 3a + 6 - 2 = 3a^2 + 15a + 16\).
06
Compute \(\frac{f(a)}{2}\)
First find \(f(a) = 3a^2 + 3a - 2\). Then, dividing by 2, \(\frac{f(a)}{2} = \frac{3a^2 + 3a - 2}{2}\). The result is simply \(\frac{3a^2}{2} + \frac{3a}{2} - 1\).
07
Evaluate \(f(2a)\)
Substitute \(x = 2a\) into the function \(f(x) = 3x^2 + 3x - 2\). Thus, \(f(2a) = 3(2a)^2 + 3(2a) - 2 = 3 \times 4a^2 + 6a - 2 = 12a^2 + 6a - 2\).
08
Add \(f(a) + f(2)\)
Find \(f(a) = 3a^2 + 3a - 2\) and \(f(2) = 16\) from previous steps. Hence, \(f(a) + f(2) = 3a^2 + 3a - 2 + 16 = 3a^2 + 3a + 14\).
09
Evaluate \(f(a+h)\)
Substitute \(x = a+h\) into the function \(f(x) = 3x^2 + 3x - 2\). Thus, \(f(a+h) = 3(a+h)^2 + 3(a+h) - 2\). Expanding \((a+h)^2 = a^2 + 2ah + h^2\), it becomes: \(3(a^2 + 2ah + h^2) + 3a + 3h - 2 = 3a^2 + 6ah + 3h^2 + 3a + 3h - 2\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Polynomials
A polynomial is a mathematical expression containing a sum of powers in one or more variables multiplied by coefficients. Polynomials are significant in mathematics because they represent a broad class of functions. In the exercise, we are given the polynomial function: \[f(x) = 3x^2 + 3x - 2\] This expression has three terms, each involving powers of the variable \(x\). Here’s a quick breakdown of this polynomial:
- The coefficient of \(x^2\) is 3, which means this polynomial is quadratic.
- The linear term is \(3x\). It affects the slope of the polynomial's graph.
- The constant term is -2, which shifts the entire graph up or down.
Using the Substitution Method
The substitution method involves replacing a variable in an expression with a given value or another expression. This method is key to function evaluation. Let's see how substitution is applied in different cases from the exercise:
- For \(f(2)\), substitute \(x = 2\) in the function, resulting in a calculation of \(3(2)^2 + 3(2) - 2\).
- For \(f\left(\frac{2}{a}\right)\), substitute \(x = \frac{2}{a}\). This changes the entire expression, requiring careful adjustments with fractions.
- In \(f(a+h)\), use substitution to introduce a new variable \(h\), demonstrating how the function behaves as \(x\) shifts slightly from \(a\).
Function Expressions Explained
Function expressions define relationships where each input has a corresponding output, typically expressed with variables like \(x\) and \(f(x)\). In this case, \[f(x) = 3x^2 + 3x - 2\] serves as a function expression indicating how each value of \(x\) is transformed through multiplication, addition, and subtraction. Here,
- \(f(x)\) reads as 'the function \(f\) of \(x\)', illustrating how \(x\) impacts the outcome.
- This form of notation is crucial for recognizing functional dependencies and applying operations systematically.
- The exercise requires evaluating these expressions at various points, like \(x = 2\) and \(x = -2\), to see how the output \(f(x)\) changes.
Simplification Techniques
Simplification is a process used to make expressions easier to interpret or compute by combining like terms or reducing complex fractions. In the exercise:
- When calculating \(2f(a)\), the original expression \(3a^2 + 3a - 2\) is multiplied by 2, leading to simplification in the expression: \(6a^2 + 6a - 4\).
- For \(\frac{f(a)}{2}\), the expression is divided by 2, simplifying each component: \(\frac{3a^2}{2} + \frac{3a}{2} - 1\).
- Expressions like \(f(a+h)\) are expanded and simplified through distribution of coefficients and combining like terms.