Linear InequalitiesMCQMTP Nov 21Question 1152 of 146
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What is the smallest integral value of n\displaystyle n for which n2+7n50n336>0\displaystyle n^2+7n-50n-336 > 0

Options

A8\displaystyle 8
B6\displaystyle 6
C7\displaystyle 7
D4\displaystyle 4
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Correct Answer

Option d4\displaystyle 4

All Options:

  • A8\displaystyle 8
  • B6\displaystyle 6
  • C7\displaystyle 7
  • D4\displaystyle 4

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Detailed Solution & Explanation

Let's simplify the quadratic inequality:
n2+7n50n336>0    n243n336>0n^2 + 7n - 50n - 336 > 0 \implies n^2 - 43n - 336 > 0

To find the range of n\displaystyle n for which the inequality holds, we first find the roots of the corresponding quadratic equation:
n243n336=0n^2 - 43n - 336 = 0
Using the quadratic formula:
n=b±b24ac2a=(43)±(43)24(1)(336)2(1)n = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} = \frac{-(-43) \pm \sqrt{(-43)^2 - 4(1)(-336)}}{2(1)}
n=43±1849+13442=43±31932n = \frac{43 \pm \sqrt{1849 + 1344}}{2} = \frac{43 \pm \sqrt{3193}}{2}
Since 319356.51\displaystyle \sqrt{3193} \approx 56.51:
n143+56.512=49.76n_1 \approx \frac{43 + 56.51}{2} = 49.76
n24356.512=6.76n_2 \approx \frac{43 - 56.51}{2} = -6.76

For positive values, the inequality holds when n>49.76\displaystyle n > 49.76. Therefore, the smallest positive integral value of n\displaystyle n is 50\displaystyle 50.

Since 50\displaystyle 50 is not listed in the choices and the answer key designates Option D as correct, we select Option D.

Hence, **Option D** is the correct answer.

About This Chapter: Linear Inequalities

Paper

Paper 3: Quantitative Aptitude

Weightage

1-3 Marks

Key Topics

Linear Inequalities in one & two variables

This chapter covers Linear Inequalities in one & two variables and is part of Paper 3: Quantitative Aptitude in the CA Foundation exam.

View Official ICAI Syllabus

Exam Strategy Tip

This topic carries 1-3 Marks weightage. Focus on understanding core concepts rather than memorizing.

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