Question

If *is a binary operation defined by $a\ast b=\frac{a}{b}+\frac{b}{a}+\frac{1}{ab}$ for positive integers $a$ and $b$ then $2\ast 5$ is equal to

• A. 4
• B. 3
• C. 2
• D. 1
• E. 5

Answer 1

Answer: (B)

$2\ast 5\frac{2}{5}+\frac{5}{2}+\frac{1}{10}$
$=\frac{4+25+1}{10}=3$