Question

Let * be a binary operation, on the set of all non-zero real numbers, given by \[a * b = \frac{ab}{5} \text { for all a, b } \in R - \left\{ 0 \right\}\]

Write the value of x given by 2 * (x * 5) = 10.

Answer 1

\[\text { Given }: \hspace{0.167em} 2 * \left( x * 5 \right) = 10 \]
\[ { Here }, \]
\[2 * \left( \frac{5x}{5} \right) = 10\]
\[ \Rightarrow 2 * x = 10\]
\[ \Rightarrow \frac{2x}{5} = 10\]
\[ \Rightarrow x = \frac{10 \times 5}{2}\]
\[ \Rightarrow x = 25\]