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Question
Which of the following is correct?
Options
(a – b)2 = a2 + 2ab – b2
(a – b)2 = a2 – 2ab + b2
(a – b)2 = a2 – b2
(a + b)2 = a2 + 2ab – b2
Solution
(a – b)2 = a2 – 2ab + b2
Explanation:
We have,
(a – b)2 = (a – b)(a – b)
= a(a – b) – b(a – b)
= a · a – a · b – b · a + b · b
= a2 – ab – ab + b2 ...[∵ a · b = b · a]
= a2 – 2ab + b2
And (a + b)2 = (a + b)(a + b)
= a · a + a · b + b · a + b · b
= a2 + 2ab + b2
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