ABC26GN0199 · Number System

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

If $a=11$ and $b=9$, then the value of $\left(\frac{a^{2}+b^{2}+a b}{a^{3}-b^{3}}\right)$ is
(a)$\frac{1}{2}$
(b)$\frac{1}{20}$
(c)2
(d)20
Answer
Answer (as printed): A
Explanation
$\frac{\left(a^{2}+b^{2}+a b\right)}{\left(a^{3}-b^{3}\right)}=\frac{a^{2}+b^{2}+a b}{(a-b)\left(a^{2}+b^{2}+a b\right)}=\frac{1}{(a-b)}=\frac{1}{(11-9)}=\frac{1}{2}$.

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

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