Which equation is the inverse of $y=16 x^2+1$ ?


A$y=\frac{ \pm \sqrt{x-1}}{4}$
B$y=\frac{ \pm \sqrt{x-1}}{16}$
C$y= \pm \sqrt{\frac{x}{16}-1}$
D$y=\frac{ \pm \sqrt{x}}{4}-\frac{1}{4}$

Verified Answer :

  • To find the inverse, replace \(y\) with \(x\) and \(x\) with \(y\) to get \(x = 16y^2 + 1\).
  • Isolate \(y^2\) by subtracting 1 and dividing by 16, resulting in \(y^2 = \frac{x - 1}{16}\).
  • Take the square root to solve for \(y\), yielding \(y = \pm \frac{\sqrt{x - 1}}{4}\).
  • The correct option is \(\boxed{a}\).

Explanation

  1. Understanding the Inverse Relation

To find the inverse of the function \(y = 16x^2 + 1\), we follow a standard algebraic procedure. An inverse function reverses the mapping of the original function. We start by writing the given equation:
\[y = 16x^2 + 1\]
The original function has a domain of all real numbers \(x\) and a range of \(y \geq 1\). When we determine the inverse, the domain of the new relation will be \(x \geq 1\), and its range will be all real numbers.

  1. Solving for y

To find the inverse, we swap the roles of \(x\) and \(y\). Replacing \(y\) with \(x\) and \(x\) with \(y\) gives:
\[x = 16y^2 + 1\]
Now, we solve this equation for \(y\). First, subtract 1 from both sides of the equation:
\[x - 1 = 16y^2\]
Next, divide both sides by 16:
\[y^2 = \frac{x - 1}{16}\]
Finally, take the square root of both sides to solve for \(y\):
\[y = \pm \sqrt{\frac{x - 1}{16}}\]

  1. Simplifying the Expression and Conclusion

We can simplify the expression for \(y\) by using the properties of square roots:
\[y = \pm \frac{\sqrt{x - 1}}{\sqrt{16}}\]
Since the square root of 16 is 4, the expression becomes:
\[y = \pm \frac{\sqrt{x - 1}}{4}\]
Comparing this result to the given options, we find it matches option (a). Thus, the inverse of the function is \(y = \frac{\pm \sqrt{x - 1}}{4}\).

Examples

Finding inverse functions is essential in various fields, such as computer graphics and cryptography. For instance, if a computer program uses a specific function to encode data, the decoding process often requires the inverse function to retrieve the original information. Similarly, in economics, if a function relates the price of an item to the quantity demanded, the inverse function allows companies to determine the price required to achieve a specific level of demand. Understanding how to algebraically manipulate equations to find inverses is a foundational skill for these and many other practical applications.