Chapter 7: Problem 16
In Exercises \(13-16,\) what happens to \(y\) when \(x\) is doubled? Here \(k\) is a positive constant. $$ \frac{y}{x^{4}}=k $$
Short Answer
Expert verified
Answer: When \(x\) is doubled, the value of \(y\) becomes 16 times greater.
Step by step solution
01
Solving for y
First, let's solve the equation for \(y\) in terms of \(x\) and the constant \(k\):
$$
\frac{y}{x^{4}} = k
$$
To isolate \(y\), multiply both sides by \(x^4\):
$$
y = kx^4
$$
Now we have an equation relating \(y\) and \(x\).
02
Doubling x
Next, let's see what happens when we double the value of \(x\). We'll replace \(x\) with \((2x)\) in the equation and see how it affects \(y\):
$$
y = k(2x)^4
$$
03
Simplify the equation
Now, let's simplify the equation to find the relationship between \(y\) and the new value of \(x\):
$$
y = k(16x^4)
$$
Observe that the right-hand side of the equation has changed from \(kx^4\) to \(16kx^4\) when we doubled the value of \(x\).
04
Comparing y-values
Contemplate how this affects the value of \(y\). When \(x\) is doubled, the right-hand side of the equation becomes \(16\) times greater:
$$
y = 16kx^4
$$
05
Conclusion
Thus, when \(x\) is doubled, the value of \(y\) becomes 16 times greater.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponentiation
Exponentiation is like supercharging a number. It allows you to multiply it by itself a certain number of times. This is commonly represented as a base raised to an exponent, written as \( x^n \). Here, \( x \) is the base and \( n \) tells you how many times to multiply it. In the exercise, we used exponentiation with \( x^4 \), which means multiplying \( x \) by itself four times: \( x \times x \times x \times x \). When you double \( x \) and then raise it to the fourth power as \( (2x)^4 \), you multiply 2 by itself four times, resulting in 16. Hence, the term \( x^4 \) in the expression for \( y \) becomes \( 16x^4 \).
- Exponentiation helps you perform multiple multiplications quickly.
- Doubling a base before raising it to a power can greatly increase the result.
- It's a core concept helping to understand growth, scaling, and other phenomena.
Direct Variation
Direct variation describes a relationship between two variables where one is a constant multiple of the other. In simpler terms, when one variable increases, the other increases at a constant rate. In the form of the equation \( y = kx^n \), \( k \) is a constant, and the change in \( x \) directly influences \( y \). For our exercise, \( y \) varies directly with \( x^4 \), which means as \( x \) changes, \( y \) will change in a predictable way dependent on \( k \).
- Direct variation allows prediction and control of outcomes by understanding one variable influences another directly.
- Improvements in technology, science, and predictions often rely on identifying and leveraging direct variations.
- It's fundamental in both linear and nonlinear relationships.
Equation Solving
Equation solving is like figuring out a puzzle. It involves finding the value of unknowns that make the equation true. We start by isolating the unknown variable, which in our exercise was \( y \). By solving the initial equation \( \frac{y}{x^4} = k \), we multiplied both sides by \( x^4 \) to isolate \( y \), giving us \( y = kx^4 \). When we double \( x \), we substitute this new value into our equation, then simplify through exponentiation: \( y = k(2x)^4 = 16kx^4 \). This shows that doubling changes the equation's entire balance and relationship.
- Equation solving makes unknowns known by revealing relationships between variables.
- This approach is crucial in science, business, and everyday problem solving.
- Understanding the step-by-step solution process is vital for mastering algebra.