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Assertion: 98 × 102 = 9996 Reason: (a + b)(a – b) = a^2 – b^2 - Mathematics

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Question

Assertion: 98 × 102 = 9996

Reason: (a + b)(a – b) = a2 – b2

Options

  • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

  • Both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A).

  • Assertion (A) is true but Reason (R) is false.

  • Assertion (A) is false but Reason (R) is true.

MCQ
Assertion and Reasoning
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Solution

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

Explanation:

Assertion: 98 × 102 = 9996 is true.

This can be evaluated using the algebraic identity:

(a + b)(a – b) = a2 – b2

Here, 98 × 102 can be seen as (100 – 2)(100 + 2).

Applying the identity:

(100 – 2)(100 + 2)

= 1002 – 22

= 10000 – 4 

= 9996

Reason states the identity used, which is true and crucial for the explanation of the assertion.

Thus, both Assertion and Reason are true and Reason correctly explains the Assertion.

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Chapter 3: Expansions - Exercise 3C [Page 74]

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Nootan Mathematics [English] Class 9 ICSE
Chapter 3 Expansions
Exercise 3C | Q 1. | Page 74
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