Question

Factorise: (l+m)2 - (l-m)2

Answer 1

Using the identity: a² - b² = (a+b)(a-b)

(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

Answer 2

Answer:

(l+m)²-(l-m)² = 4lm

Step-by-step explanation:

Given ,

(l+m)²-(l-m)²

= [(l+m)+(l-m)][(l+m)-(l-m))]

/* By algebraic identity:

a²-b² = (a+b)(a-b)*/

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

=2l × 2m

= 4lm

Therefore,

(l+m)²-(l-m)² = 4lm

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