Question

Use substitution to compose the two functions. $$ p=2 q^{4} \text { and } D=5 p-1 $$

Short answer

Question: Using substitution, combine the functions p and D, where $$p = 2q^4$$ and $$D = 5p - 1$$. Find D in terms of q. Answer: $$D(q) = 10q^4 - 1$$.

Step-by-step solution

Identify the functions

We are given two functions: - $$p = 2q^4$$ - $$D = 5p - 1$$ Our goal is to use substitution to compose these two functions and find D in terms of q.

Substitute the first function into the second function

We will substitute the equation for p in terms of q into the second function: $$D = 5(2q^4) - 1$$

Simplify the expression

Now, simplify the expression: $$D = 10q^4 - 1$$

Write the final result

The composed function for D in terms of q is: $$D(q) = 10q^4 - 1$$

Key concepts

Substitution Method

The substitution method is a powerful technique often used in algebra to simplify complex expressions or equations. In this method, one expression is replaced with another to find a solution or simplify the problem. This is a common approach when dealing with composed functions, where you have two functions and you need to express one in terms of the other.

• Step 1: Identify the independent variable or the inner function that you can substitute.
• Step 2: Replace the inner function’s expression with the substituting expression.
• Step 3: Simplify the resulting expression to make it easier to understand or solve.

In our example, we substitute the equation given for \( p \) into the equation for \( D \). This transforms the problem from a two-variable function into a single variable equation involving \( q \), making it easier to compute further values.

Algebraic Manipulation

Algebraic manipulation is the process of rearranging and simplifying algebraic expressions to either solve them or transform them into a more useful form. This skill is crucial when working with polynomial expressions as it allows you to simplify them, combine like terms, and find results more efficiently. To perform algebraic manipulation, you should:

• Follow the order of operations: parentheses, exponents, multiplication/division (from left to right), addition/subtraction (from left to right).
• Distribute multiplication across addition or subtraction (i.e., apply the distributive property).
• Simplify by combining like terms.

In the exercise provided, substitution reduced the second equation to \( D = 5(2q^4) - 1 \). From there, applying distributive property and simplifying, it resulted in the expression \( D = 10q^4 - 1 \). This showcases using multiplication first, then simple subtraction from the operation order rule.

Polynomial Functions

Polynomial functions are expressions consisting of variables and coefficients, involving only the operations of addition, subtraction, multiplication, and non-negative integer exponents of variables. A polynomial might look complex initially due to the presence of different powers, but they have a regular structure that makes them predictable and manageable. Common characteristics of polynomial functions include:

• The degree of the polynomial, which is the highest power of the variable in the expression (e.g., \( q^4 \) makes it a fourth-degree polynomial).
• A leading coefficient, which is the coefficient of the term with the highest degree (e.g., \( 10 \) in \( 10q^4 \)).
• A constant term, potentially included as in \( 10q^4 - 1 \), where \(-1\) is the constant term.

Polynomials are used extensively in mathematics and engineering, providing a fundamental form that describes a variety of phenomena due to their simple yet versatile structure. In our example, \( D(q) = 10q^4 - 1 \) exemplifies a polynomial with a single variable, where understanding its components helps in analyzing the function's behavior.