18. (l + m)^2
(l - m)^2
Answers
Answered by
0
Answer:
Step-by-step explanation:
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
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Answered by
0
Answer:
(l+m)²(l-m)²=l^4+m^4-2l²m²
Step-by-step explanation:
Given that,
(l+m)²(l-m)²
as we know that,
(a+b)²=a²+b²+2ab
& (a-b)²=a²+b²-2ab
here,a=l & b=m
now,
(l+m)²(l-m)²=(l²+m²+2lm)(l²+m²-2lm)
⇒l^4+l²m²-2l³m+m²l²+m^4-2lm³+2l³m+2lm³-4l²m² (∵by multiplying)
⇒l^4+m^4+2m²l²-4l²m² (∵By cancelling)
⇒l^4+m^4-2l²m²
∴(l+m)²(l-m)²=l^4+m^4-2l²m²
HOPE THIS WOULD BE HELPFUL FOR YOU
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