ABC26GN0189 · Number System

Subject: General Aptitude · Chapter: Number System · Exam: 2010 · Marks: · Difficulty:

If $a$ and $b$ be positive integers such that $a^{2}-b^{2}=19$, then the value of $a$ is

(a)9

(b)10

(c)19

(d)20

Answer

Answer (as printed): B

Explanation

$\left(a^{2}-b^{2}\right)=19 \Rightarrow(a+b)(a-b)=19$. Clearly, $a=10$ and $b=9$.

Explanation as extracted from the printed page; notation may be imperfect.