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गुणनखंड

Question
CBSEHHIMAH8004080

गुणनखंड कीजिए:
(l + m)2 - (l-m)2

Solution

(l + m)2 - (l-m)2 = [(l + m) + (l -m)][(l + m) - (l - m)]
                              [∵ a- b2 = (a+b)(a-b)]
                        = [l + m + l - m][l + m - l + m]
                        = (2l)(2m) = 2cross times 2(l × m)
                        = 4lm