KCET · Maths · Mathematical Reasoning
The inverse of 2010 in the group \(\mathrm{Q}^{+}\)of all positive rational under the binary operation * defined by \(\mathrm{a}\) * \(\mathrm{b}=\frac{\mathrm{ab}}{2010}, \forall \mathrm{a}, \mathrm{b} \in \mathrm{Q}^{+}\), is
- A 2009
- B 2011
- C 1
- D 2010
Answer & Solution
Correct Answer
(D) 2010
Step-by-step Solution
Detailed explanation
By inspection of binary operation \((*)\) over;
\[
\mathrm{a} * \mathrm{~b}=\frac{\mathrm{ab}}{2010}, \forall \mathrm{a}, \mathrm{b}, \in \mathrm{Q}^{+}
\]
2010 is the identity element.
And also we know that, the inverse of identity element is itself identity element.
Hence, inverse of \(2010=2010\)
\[
\mathrm{a} * \mathrm{~b}=\frac{\mathrm{ab}}{2010}, \forall \mathrm{a}, \mathrm{b}, \in \mathrm{Q}^{+}
\]
2010 is the identity element.
And also we know that, the inverse of identity element is itself identity element.
Hence, inverse of \(2010=2010\)
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