Question:

If x = log (y +√y2 + 1 ) then y =

Updated On: May 4, 2026
  • tanh x

  • coth x

  • sinh x

  • cosh x

Show Solution
collegedunia
Verified By Collegedunia

The Correct Option is C

Solution and Explanation

To determine the value of \( y \) in terms of \( x \), given \( x = \log\left(y + \sqrt{y^2 + 1}\right) \), we proceed as follows:

  1. Convert to exponential form: \[ e^x = y + \sqrt{y^2 + 1} \]
  2. Isolate the square root: \[ e^x - y = \sqrt{y^2 + 1} \]
  3. Square both sides: \[ (e^x - y)^2 = y^2 + 1 \]
  4. Expand: \[ e^{2x} - 2ye^x + y^2 = y^2 + 1 \]
  5. Cancel \( y^2 \): \[ e^{2x} - 2ye^x = 1 \]
  6. Solve for \( y \): \[ 2ye^x = e^{2x} - 1 \quad \Rightarrow \quad y = \frac{e^{2x} - 1}{2e^x} \]
  7. Recognize the identity: \[ y = \frac{e^x - e^{-x}}{2} \]

Thus, the value of \( y \) is:

\( \sinh x \)

Was this answer helpful?
0
0

Concepts Used:

Quadratic Equations

A polynomial that has two roots or is of degree 2 is called a quadratic equation. The general form of a quadratic equation is y=ax²+bx+c. Here a≠0, b, and c are the real numbers

Consider the following equation ax²+bx+c=0, where a≠0 and a, b, and c are real coefficients.

The solution of a quadratic equation can be found using the formula, x=((-b±√(b²-4ac))/2a)

Two important points to keep in mind are:

  • A polynomial equation has at least one root.
  • A polynomial equation of degree ‘n’ has ‘n’ roots.

Read More: Nature of Roots of Quadratic Equation

There are basically four methods of solving quadratic equations. They are:

  1. Factoring
  2. Completing the square
  3. Using Quadratic Formula
  4. Taking the square root