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Question

If $\frac{a+1}{a^2-1} = \frac{1}{5}$, then the value of $a$ is -

The correct answer is
5

Algebraic Equation Value for 'a'

We are given the equation: $ \frac{a+1}{a^2-1} = \frac{1}{5} $ Our objective is to determine the value of the variable $a$.

Equation Simplification Steps

First, simplify the denominator $a^2-1$. This is a difference of squares, which factors as:

$ a^2-1 = (a-1)(a+1) $

Substitute this factorization back into the original equation:

$ \frac{a+1}{(a-1)(a+1)} = \frac{1}{5} $

Solving for Variable 'a'

Provided that $a \neq -1$ (which means $a+1 \neq 0$), we can cancel the $(a+1)$ term from both the numerator and the denominator:

$ \frac{1}{a-1} = \frac{1}{5} $

This simplified equation implies that the denominators must be equal:

$ a-1 = 5 $

To find the value of $a$, add 1 to both sides of the equation:

$ a = 5 + 1 $ $ a = 6 $

We must verify our assumption that $a \neq -1$. Since $a=6$, the condition $6 \neq -1$ holds true, confirming the validity of the cancellation step.

Thus, the calculated value of $a$ is 6.

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Important Questions from Identities

  1. If $x + y + z = 10$, $x^2 + y^2 + z^2 = 38$, $5xyz = 150$ and $(xy + yz + zx) = 31$, then what is the value of $2(x^3 + y^3 + z^3)$?
  2. If $x = \sqrt[3]{31 + 14\sqrt{3}}$ and $y = \sqrt[3]{31 - 14\sqrt{3}}$, then the value of $x^3 + y^3 + 3x^3y^3$ is
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