Chapter 5: Problem 66
Find the specified function values. Find \(Q(3)\) and \(Q(-1): Q(x)=-4 x^{3}+7 x^{2}-6\)
Short Answer
Expert verified
Q(3) = -51 and Q(-1) = 5.
Step by step solution
01
- Understand the Given Function
Identify the given function. Here, the function is given as Q(x) = -4x^3 + 7x^2 - 6. Our task is to find the values of Q(3) and Q(-1).
02
- Substitute x with 3 to Find Q(3)
Replace x with 3 in the function Q(x). This gives us: Q(3) = -4(3)^3 + 7(3)^2 - 6. Now, calculate each term: Q(3) = -4(27) + 7(9) - 6 Q(3) = -108 + 63 - 6.
03
- Simplify Q(3)
Add the previous results to find Q(3): Q(3) = -108 + 63 - 6 Q(3) = -108 + 57 Q(3) = -51.
04
- Substitute x with -1 to Find Q(-1)
Replace x with -1 in the function Q(x). This gives us: Q(-1) = -4(-1)^3 + 7(-1)^2 - 6. Now, calculate each term: Q(-1) = -4(-1) + 7(1) - 6 Q(-1) = 4 + 7 - 6.
05
- Simplify Q(-1)
Add the previous results to find Q(-1): Q(-1) = 4 + 7 - 6 Q(-1) = 5.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Substitution
Function substitution means replacing the variable in a function with a given value. This helps us find the function's output for specific inputs. For instance, if we have a function Q(x)=-4x^3 + 7x^2 - 6, and we need to find Q(3), we substitute x with 3.
Substitution changes the function to: Q(3) = -4(3)^3 + 7(3)^2 - 6.
Remember to carefully follow the order of operations:Calculate the exponents Then multiply Finally, add or subtract the results. This method allows precise solutions specific to the input values.
Substitution changes the function to: Q(3) = -4(3)^3 + 7(3)^2 - 6.
Remember to carefully follow the order of operations:
Polynomials
Polynomials are a type of algebraic expression that include variables raised to whole number powers and their coefficients. In the function Q(x)=-4x^3 + 7x^2 - 6,
Q(x) is a cubic polynomial because the highest power of x is 3.
Here are the components of our polynomial:The term -4x^3 is the cubic term. The term 7x^2 is the quadratic term. The term -6 is the constant term. Polynomials are vital in algebra because they can represent complex relationships and have multiple uses in calculus and real-world problems.
Q(x) is a cubic polynomial because the highest power of x is 3.
Here are the components of our polynomial:
Algebraic Expressions
Algebraic expressions combine variables, coefficients, and constants using arithmetic operations. In our exercise, Q(x)=-4x^3 + 7x^2 - 6 is an algebraic expression.
Breaking it down:-4x^3 represents 'minus four times x cubed,' 7x^2 means 'seven times x squared,' -6 is the constant. When working with algebraic expressions: Identify each term and its components. Observe how terms are connected using + or - signs. Simplifying algebraic expressions requires correctly following arithmetic rules and operations.
Breaking it down:
Step-by-Step Solution
Solving problems step-by-step ensures that we don't miss crucial parts and helps us understand each process. Here's a simplified approach for our exercise.
First, we copy the given polynomial: Q(x) = -4x^3 + 7x^2 - 6.
Next, for Q(3), we substitute x with 3: Q(3) = -4(3)^3 + 7(3)^2 - 6.
Evaluate each component: -4(27) + 7(9) - 6 = -108 + 63 - 6
Finally, add the results to get Q(3) = -51.
Repeat these steps for Q(-1): Q(-1) = -4(-1)^3 + 7(-1)^2 - 6
Evaluate the terms: -4(-1) + 7(1) - 6 = 4 + 7 - 6
Add the results to find Q(-1) = 5.
This step-by-step method helps you approach any similar problems systematically.
First, we copy the given polynomial: Q(x) = -4x^3 + 7x^2 - 6.
Next, for Q(3), we substitute x with 3: Q(3) = -4(3)^3 + 7(3)^2 - 6.
Evaluate each component: -4(27) + 7(9) - 6 = -108 + 63 - 6
Finally, add the results to get Q(3) = -51.
Repeat these steps for Q(-1): Q(-1) = -4(-1)^3 + 7(-1)^2 - 6
Evaluate the terms: -4(-1) + 7(1) - 6 = 4 + 7 - 6
Add the results to find Q(-1) = 5.
This step-by-step method helps you approach any similar problems systematically.