Answers

2014-06-17T16:46:17+05:30
(l+m)²-(l-m)²
=l²+2lm+m²-l²+2lm-m²
=4ml
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2014-06-17T17:16:24+05:30
Expand the terms
(l^2 +2lm+ m^2)-(l^2 - 2lm+m^2)
all terms get cancelled and the answer is 4lm
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