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JEE Mathematics 2026 Question with Solution

Let A={x:x2106}A = \{x : |x^2 - 10| \le 6\} and B={x:x2>1}B = \{x : |x - 2| > 1\}. Then

  • A

    AB=[2,3]A - B = [2, 3]

  • B

    AB=[4,2][3,4]A \cap B = [-4, -2] \cup [3, 4]

  • C

    BA=(,4)(2,1)(4,)B - A = (-\infty, -4) \cup (-2, 1) \cup (4, \infty)

  • D

    AB=(,1](2,)A \cup B = (-\infty, 1] \cup (2, \infty)

Answer

Correct answer:C

Step-by-step solution

Standard Method

Given: A={x:x2106}A = \{x : |x^2 - 10| \le 6\} and B={x:x2>1}B = \{x : |x - 2| > 1\}.

Find: Which set relation is correct.

For set AA,

6x2106-6 \le x^2 - 10 \le 6

So,

4x2164 \le x^2 \le 16

Hence,

2x42 \le |x| \le 4

Therefore,

A=[4,2][2,4]A = [-4, -2] \cup [2, 4]

For set BB,

x2>1|x - 2| > 1

This gives

x2>1 or x2<1x - 2 > 1 \text{ or } x - 2 < -1

So,

x>3 or x<1x > 3 \text{ or } x < 1

Therefore,

B=(,1)(3,)B = (-\infty, 1) \cup (3, \infty)

Now evaluate BAB - A. This means elements of BB that are not in AA. The complement used in the solution is

Ac=(,4)(2,2)(4,)A^c = (-\infty, -4) \cup (-2, 2) \cup (4, \infty)

Thus,

BAc=((,1)(3,))((,4)(2,2)(4,))B \cap A^c = \left(( -\infty, 1) \cup (3, \infty)\right) \cap \left(( -\infty, -4) \cup (-2, 2) \cup (4, \infty)\right)

which gives

(,4)(2,1)(4,)(-\infty, -4) \cup (-2, 1) \cup (4, \infty)

So,

BA=(,4)(2,1)(4,)B - A = (-\infty, -4) \cup (-2, 1) \cup (4, \infty)

Therefore, the correct option is C.

The solution also notes that option A is technically correct since

AB=[2,3]A - B = [2, 3]

but the extracted solution concludes that option C is the correct representation.

Checking the options one by one

From the solved sets,

A=[4,2][2,4],B=(,1)(3,)A = [-4, -2] \cup [2, 4], \qquad B = (-\infty, 1) \cup (3, \infty)

Option A:

AB=ABcA - B = A \cap B^c

Since

Bc=[1,3]B^c = [1, 3]

we get

AB=([4,2][2,4])[1,3]=[2,3]A - B = ([-4, -2] \cup [2, 4]) \cap [1, 3] = [2, 3]

So this statement is true.

Option B:

AB=([4,2][2,4])((,1)(3,))A \cap B = ([-4, -2] \cup [2, 4]) \cap ((-\infty, 1) \cup (3, \infty))

Hence,

AB=[4,2](3,4]A \cap B = [-4, -2] \cup (3, 4]

This is not equal to [4,2][3,4][-4, -2] \cup [3, 4], so option B is false because 3B3 \notin B.

Option C:

BA=(,4)(2,1)(4,)B - A = (-\infty, -4) \cup (-2, 1) \cup (4, \infty)

This matches the derived result, so option C is true.

Option D:

AB=((,1)(3,))([4,2][2,4])A \cup B = ((-\infty, 1) \cup (3, \infty)) \cup ([-4, -2] \cup [2, 4])

which simplifies to

(,1)[2,)(-\infty, 1) \cup [2, \infty)

This is not equal to (,1](2,)(-\infty, 1] \cup (2, \infty), so option D is false.

Thus, from the provided solution, the selected answer is C, even though option A also evaluates correctly.

Common mistakes

  • A common mistake is solving x2106|x^2 - 10| \le 6 as only x2106x^2 - 10 \le 6. This ignores the lower bound from the absolute value. Use 6x2106-6 \le x^2 - 10 \le 6 before solving.

  • Students often write x2>1|x - 2| > 1 as 1<x<31 < x < 3, which is the interval for x2<1|x - 2| < 1. For a greater-than absolute value inequality, the solution lies outside the interval, so x<1x < 1 or x>3x > 3.

  • Another mistake is including boundary points incorrectly. Since x2>1|x - 2| > 1 is a strict inequality, x=1x = 1 and x=3x = 3 are not in BB. This is why intervals for BB are open at those points.

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