Question

18. (l + m)² - (l - m)² =​

Answer 1

Answer:

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Answer 2

Answer:

(l+m)^2-(l-m)^2

={(l+m)+(l-m)}{(l+m)-(l-m)}

=(l+m+l-m)(l+m-l+m)

=2l.2m

=4lm