Question

evaluate the following using suitable identities a)21³-15³. b)249×241​

Answer 1

Answer:

We know that,

If (a+b+c)=0, then a

3

+b

3

+c

3

=3abc

Here, 28+(−15)+(−13)=0

∴(28)

3

+(−15)

3

+(−13)

3

=3(28)(−15)(−13)=16380

Answer 2

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