Question

${11}^2-1$ is a product of two consecutive even numbers. Find those two even numbers.

• A. 12 and 22
• B. 12 and 13
• C. 10 and 12
• D. 12 and 14

Answer 1

The correct option is C 10 and 12

${11}^2-1=120$
We can express the above number into general form $a^2-1=(a+1)\times (a-1)$
Where $a=11$
So, ${11}^2-1=(11+1)\times (11-1)$ $=12\times 10=120$
Therefore, the two even consecutive numbers are 10 and 12.