Chapter 3: Problem 55
If \(f(x)=3 x+3, g(x)=4 x^{2}-6 x+3,\) and \(h(x)=5 x^{2}-7\) find the following. $$ h(-3) $$
Short Answer
Expert verified
38
Step by step solution
01
Identify the function
First, determine which function is needed to solve this exercise. Since the question asks for \( h(-3) \), we will use the function \( h(x) = 5x^2 - 7 \).
02
Substitute -3 into the function
Replace \( x \) with \(-3\) in the function \( h(x) = 5x^2 - 7 \). This gives us \( h(-3) = 5(-3)^2 - 7 \).
03
Calculate \(-3^2\)
Calculate \((-3)^2\), which is \( 9 \).
04
Multiply by 5
Multiply the result from Step 3 by 5. So, \( 5 imes 9 = 45 \).
05
Subtract 7
Subtract 7 from the result of Step 4. So, \( 45 - 7 = 38 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Substitution in Functions
Substitution in functions is a fundamental concept in algebra that involves replacing the variable in a function with a specific number or expression. It's like filling in a blank with a specific value to see what the outcome will be. In this case, we need to find the value of the function for a given input. For example, when evaluating the function \( h(x) = 5x^2 - 7 \) for \( x = -3 \), you simply replace every "\( x \)" in the function with "\( -3 \)". This substitution gives us \( h(-3) = 5(-3)^2 - 7 \). A few key points to remember while doing substitution are:
- Replace every occurrence of the variable with the given value.
- Be cautious of signs, especially with negative values and exponents.
- Follow the order of operations: parentheses, exponents, multiplication, and addition/subtraction.
Function Notation
Function notation is a way to name a function and indicate the input value. It’s commonly written as \( f(x) \). The "\( f \)" stands for the function's name, while the "\( x \)" inside the parentheses represents the variable or input. This form clearly conveys the function's rule in terms of its variable.
For example, in our problem, we have three functions: \( f(x) = 3x + 3 \), \( g(x) = 4x^2 - 6x + 3 \), and \( h(x) = 5x^2 - 7 \). Here, "\( h(x) \)" represents the function that we are working with. In this case:
For example, in our problem, we have three functions: \( f(x) = 3x + 3 \), \( g(x) = 4x^2 - 6x + 3 \), and \( h(x) = 5x^2 - 7 \). Here, "\( h(x) \)" represents the function that we are working with. In this case:
- "\( h \)" is the name of the function, helping to differentiate it from other functions like \( f \) and \( g \).
- "\( x \)" is the variable input, which can be replaced by any number.
- When you see something like \( h(-3) \), it specifies that the input value is \( -3 \).
Quadratic Functions
Quadratic functions are a type of polynomial function that typically feature a squared term and take the standard form \( ax^2 + bx + c \). These functions create a parabolic shape when graphed, which can open upwards or downwards depending on the sign of the leading coefficient. In the given exercise, the function \( h(x) = 5x^2 - 7 \) is a quadratic function.
Quadratic functions are characterized by:
Quadratic functions are characterized by:
- The degree of the polynomial being two, with the highest exponent on the \( x \) term being 2.
- Having a curve known as a parabola whose direction depends on the coefficient \( a \). Here, \( a = 5 \), which is positive, meaning it opens upwards.
- The vertex of the parabola, which for simple forms like \( ax^2 + c \), is at the point \((0, c)\).