Mathematics
Assertion (A) : If we add 9 with 49x2 - 42x, the resultant expression will be a perfect square expression.
Reason (R) : The product of the sum and difference of the same two terms = Difference of their squares.
Both A and R are correct, and R is the correct explanation for A.
Both A and R are correct, and R is not the correct explanation for A.
A is true, but R is false.
A is false, but R is true.
Identities
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Answer
Given: 49x2 - 42x
Adding 9 in it the term the expression becomes
⇒ 49x2 - 42x + 9
⇒ (7x)2 - 2 × (7x) × 3 + (3)2
⇒ (7x - 3)2
The resultant expression will be a perfect square expression.
So, assertion (A) is true.
The product of the sum and difference of the same two terms = Difference of their squares.
(a + b)(a - b) = a2 - b2
So, reason (R) is true but reason (R) is not the correct explanation of assertion (A).
Hence, option 2 is the correct option.
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