$$\frac{768 \times 768 \times 768 + 232 \times 232 \times 232}{768 \times 768 - 768 \times 232 + 232 \times 232} = x$$
Aptitude
Number System
Difficulty: Medium
Choose an option
-
A1000
-
B536
-
C500
-
D268
-
ENone of these
Answer
Correct Answer: 1000
Explanation
### Concept & Formula
This mathematical expression maps perfectly to the factorization of the sum of two perfect cubes. The large numbers are merely placeholders for variables in a standard formula.
$$a^3 + b^3 = (a + b)(a^2 - ab + b^2)$$
### Step-by-Step Solution
* Identify the recurring large numbers and assign them to algebraic variables:
* Let $a = 768$
* Let $b = 232$
* Rewrite the provided fraction completely in terms of $a$ and $b$:
$$\frac{a \times a \times a + b \times b \times b}{a \times a - a \times b + b \times b}$$
* Simplify the expression using cube and square exponents:
$$\frac{a^3 + b^3}{a^2 - ab + b^2}$$
* Expand the numerator using the standard sum of cubes algebraic identity:
$$\frac{(a + b)(a^2 - ab + b^2)}{a^2 - ab + b^2}$$
* The large trinomial $(a^2 - ab + b^2)$ is present in both the numerator and the denominator, so they cancel each other out completely:
$$a + b$$
* Substitute the original numerical values back into the simplified expression and evaluate:
$$768 + 232 = 1000$$
### Exam Strategy & Shortcut
Memorize the structural form $\frac{a^3 + b^3}{a^2 - ab + b^2}$. When you spot a sum of three multiplied identical terms in the numerator and a corresponding mix of squares in the denominator, the answer is always simply $a + b$. Mentally add the two unique numbers in the problem ($768 + 232$) to arrive at 1000 instantly.
### Common Pitfall
Students frequently panic at the sight of massive multiplication operations and attempt digit-by-digit calculation, which is a guaranteed way to run out of time on an aptitude test. Always look for algebraic reductions first.
### Final Answer
Therefore, the correct answer is **1000**.