The sum of the squares of two numbers is $3341$ and the difference of their squares is $891$. The numbers are
Aptitude
Problems on Numbers
Difficulty: Medium
Choose an option
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A25, 36
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B25, 46
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C35, 46
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DNone of these
Answer
Correct Answer: 35, 46
Explanation
### Concept & Formula
This problem simplifies to a basic system of linear equations if you treat the squares of the numbers as single variables (e.g., let $A = x^2$ and $B = y^2$).
$$x^2 + y^2 = \text{Sum}$$
$$x^2 - y^2 = \text{Difference}$$
### Step-by-Step Solution
* **Given:** Let the two numbers be $x$ and $y$.
* Equation 1: $x^2 + y^2 = 3341$
* Equation 2: $x^2 - y^2 = 891$
* To find $x^2$, add Equation 1 and Equation 2:
$$(x^2 + y^2) + (x^2 - y^2) = 3341 + 891$$
$$2x^2 = 4232$$
* Divide by $2$:
$$x^2 = 2116$$
* Take the square root to find $x$:
$$x = \sqrt{2116} = 46$$
* To find $y^2$, subtract Equation 2 from Equation 1:
$$(x^2 + y^2) - (x^2 - y^2) = 3341 - 891$$
$$2y^2 = 2450$$
* Divide by $2$:
$$y^2 = 1225$$
* Take the square root to find $y$:
$$y = \sqrt{1225} = 35$$
* The numbers are $46$ and $35$.
### Exam Strategy & Shortcut
Instead of full square root extraction, use **Unit Digits**. We know $2x^2 = 4232$, so $x^2$ ends in $6$. The square roots of numbers ending in $6$ must end in $4$ or $6$. Option (c) has $46$, which fits. Similarly, $2y^2 = 2450 \Rightarrow y^2 = 1225$. A square ending in $25$ guarantees the root ends in $5$. Option (c) contains $35$ and $46$, seamlessly matching the unit digit logic without doing the heavy lifting of calculating $\sqrt{2116}$.
### Common Pitfall
Students often get intimidated by large numbers like $3341$ and $2116$ and assume they made an arithmetic error. Do not panic; trust the linear elimination method. Keep track of which variable is the larger one to match the options correctly (though options here are pairs).
### Final Answer
**Therefore, the correct answer is 35, 46.**