Question

Evaluate i) 209X209 and it) 105 x 95 using suitable identities
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Answer 1

i) (a+b)² = a²+2ab+b²

-> (200+9)²

200² + 2×200×9 + 9²

40000+3600+81

=43681

ii) (a+b) (a-b) = a² - b²

(100+5) (100-5)